diff --git a/achievement.cpp b/achievement.cpp
index c2e60a6b..7f7632cc 100644
--- a/achievement.cpp
+++ b/achievement.cpp
@@ -187,6 +187,8 @@ void achievement_gain(const char* s, char flags IS(0)) {
 EX void achievement_collection(eItem it) {
   if(cheater) return;
   if(randomPatternsMode) return;
+  LATE( achievement_collection(it); )
+
   int q = items[it];
   
   if(it == itTreat && q == 50 && (geometry == gSphere || geometry == gElliptic) && BITRUNCATED) 
@@ -518,6 +520,8 @@ EX void achievement_count(const string& s, int current, int prev) {
   if(cheater) return;
   if(shmup::on) return;
   if(randomPatternsMode) return;
+  LATE( achievement_count(s, current, prev); )
+
   if(s == "GOLEM" && current >= 5)
     achievement_gain("GOLEM2");
   if(s == "GOLEM" && current >= 10)
@@ -563,6 +567,7 @@ int specific_what = 0;
 
 EX void improve_score(int i, eItem what) {
   if(offlineMode) return;
+  LATE( improve_score(i, what); )
 #ifdef HAVE_ACHIEVEMENTS
   if(haveLeaderboard(i)) updateHi(what, get_currentscore(i));
   if(items[what] && haveLeaderboard(i)) {
@@ -579,6 +584,7 @@ EX void achievement_score(int cat, int number) {
   if(offlineMode) return;
 #ifdef HAVE_ACHIEVEMENTS
   if(cheater) return;
+  LATE( achievement_score(cat, number); )
   if(cat == LB_HALLOWEEN) {
     if(geometry != gSphere && geometry != gElliptic)
       return;
@@ -597,6 +603,7 @@ EX void achievement_score(int cat, int number) {
   }
 
 EX void improveItemScores() {
+  LATE( improveItemScores(); )
   for(int i=1; i<=12; i++) improve_score(i, eItem(i));
   improve_score(17, itOrbYendor);
   improve_score(18, itFernFlower);
@@ -669,6 +676,8 @@ int next_stat_tick;
 EX void achievement_final(bool really_final) {
   if(offlineMode) return;
 
+  LATE( achievement_final(really_final); )
+
 #ifdef HAVE_ACHIEVEMENTS
   if(ticks > next_stat_tick) {
     upload_score(LB_STATISTICS, time(NULL));
@@ -778,6 +787,7 @@ EX void check_total_victory() {
   if(!items[itHolyGrail]) return;
   if(items[itHyperstone] < 50) return;
   if(!princess::reviveAt) return;
+  LATE( check_total_victory(); )
   hadtotalvictory = true;
   achievement_gain("TOTALVICTORY");
   }
@@ -798,6 +808,7 @@ EX void achievement_victory(bool hyper) {
   if(peace::on) return;
   if(tactic::on) return;
   if(chaosmode) return;
+  LATE( achievement_victory(hyper); )
   DEBB(DF_STEAM, ("after checks"))
 
   int t = getgametime();
diff --git a/attack.cpp b/attack.cpp
index abbc3ebe..0d489e9c 100644
--- a/attack.cpp
+++ b/attack.cpp
@@ -213,6 +213,7 @@ EX bool petrify(cell *c, eWall walltype, eMonster m) {
         
 EX void killIvy(cell *c, eMonster who) {
   if(c->monst == moIvyDead) return;
+  changes.ccell(c);
   if(checkOrb(who, itOrbStone)) petrify(c, waPetrified, c->monst);
   c->monst = moIvyDead; // NEWYEARFIX
   for(int i=0; i<c->type; i++) if(c->move(i))
@@ -222,6 +223,7 @@ EX void killIvy(cell *c, eMonster who) {
 
 EX void prespill(cell* c, eWall t, int rad, cell *from) {
   if(againstWind(c, from)) return;
+  changes.ccell(c);
   // these monsters block spilling
   if(c->monst == moSeep || c->monst == moVineSpirit || c->monst == moShark ||
     c->monst == moGreaterShark || c->monst == moParrot || c->monst == moCShark)
@@ -300,7 +302,10 @@ EX void prespill(cell* c, eWall t, int rad, cell *from) {
   }
 
 EX void spillfix(cell* c, eWall t, int rad) {
-  if(c->wall == waTemporary) c->wall = t;
+  if(c->wall == waTemporary) {
+    changes.ccell(c);
+    c->wall = t;
+    }
   if(rad) for(cell *c2: adj_minefield_cells(c))
     spillfix(c2, t, rad-1);
   }
@@ -314,12 +319,14 @@ EX void degradeDemons() {
   int dcs = isize(dcal);
   for(int i=0; i<dcs; i++) {
     cell *c = dcal[i];
-    if(c->monst == moGreaterM || c->monst == moGreater)
+    if(c->monst == moGreaterM || c->monst == moGreater) {
+      changes.ccell(c);
       achievement_gain("DEMONSLAYER");
-    if(c->monst == moGreaterM) c->monst = moLesserM;
-    if(c->monst == moGreater) c->monst = moLesser;
-    shmup::degradeDemons();
+      if(c->monst == moGreaterM) c->monst = moLesserM;
+      if(c->monst == moGreater) c->monst = moLesser;
+      }
     }  
+  shmup::degradeDemons();
   }
 
 EX void stunMonster(cell *c2, eMonster killer, flagtype flags) {
@@ -367,6 +374,7 @@ EX bool attackJustStuns(cell *c2, flagtype f, eMonster attacker) {
   }
   
 EX void minerEffect(cell *c) {
+  changes.ccell(c);
   eWall ow = c->wall;
   if(c->wall == waOpenGate || c->wall == waFrozenLake || c->wall == waBoat ||
     c->wall == waStrandedBoat ||
@@ -390,6 +398,7 @@ EX void minerEffect(cell *c) {
 
 EX void killMutantIvy(cell *c, eMonster who) {
   if(checkOrb(who, itOrbStone)) petrify(c, waPetrified, moMutant);
+  changes.ccell(c);
   removeIvy(c);
   for(int i=0; i<c->type; i++)
     if(c->move(i)->mondir == c->c.spin(i) && (isMutantIvy(c->move(i)) || c->move(i)->monst == moFriendlyIvy))
@@ -461,17 +470,18 @@ EX void killMonster(cell *c, eMonster who, flagtype deathflags IS(0)) {
     bool avenge = false;
     for(int i=0; i<c->type; i++) if(!isWarpedType(c->move(i)->land))
       avenge = true;
-    if(avenge) { avengers += 2; }
+    if(avenge)
+      changes.value_add(avengers, 2);
     }
   
   if(m == moMirrorSpirit && who != moMimic && !(deathflags & (AF_MAGIC | AF_CRUSH))) {
     kills[m]--;
-    mirrorspirits++;
+    changes.value_inc(mirrorspirits);
     }
   
   if(isMutantIvy(m) || m == moFriendlyIvy) {
     pcount = 0;
-    if(isMutantIvy(m)) clearing::direct++;
+    if(isMutantIvy(m)) changes.at_commit([] { clearing::direct++; });
     bignum s = ivy_total() - 1;
     killMutantIvy(c, who);
     s = ivy_total() - s;
@@ -481,6 +491,7 @@ EX void killMonster(cell *c, eMonster who, flagtype deathflags IS(0)) {
   
   if(m == moPrincess) {
     princess::info *i = princess::getPrincessInfo(c);
+    changes.value_keep(*i);
     if(i) {
       i->princess = NULL;
       if(i->bestdist == OUT_OF_PALACE) {
@@ -523,15 +534,19 @@ EX void killMonster(cell *c, eMonster who, flagtype deathflags IS(0)) {
   if(m == moIceGolem) {
     if(petrify(c, waIcewall, m)) pcount = 0;
     heat::affect(c, -1);
-    forCellEx(c2, c) heat::affect(c2, -.5);
+    forCellEx(c2, c) {
+      changes.ccell(c2);      
+      heat::affect(c2, -.5);
+      }
     }
     
   if(m == moTroll) {
     petrify(c, waDeadTroll, m); pcount = 0;
-    for(int i=0; i<c->type; i++) if(c->move(i)) {
-      c->move(i)->item = itNone;
-      if(c->move(i)->wall == waDeadwall || c->move(i)->wall == waDeadfloor2) c->move(i)->wall = waCavewall;
-      if(c->move(i)->wall == waDeadfloor) c->move(i)->wall = waCavefloor;
+    forCellEx(c1, c) {
+      changes.ccell(c1);
+      c1->item = itNone;
+      if(c1->wall == waDeadwall || c1->wall == waDeadfloor2) c1->wall = waCavewall;
+      if(c1->wall == waDeadfloor) c1->wall = waCavefloor;
       }
     }
   if(m == moFjordTroll || m == moForestTroll || m == moStormTroll) {
@@ -543,14 +558,16 @@ EX void killMonster(cell *c, eMonster who, flagtype deathflags IS(0)) {
     destroyHalfvine(c);
     minerEffect(c);
     brownian::dissolve_brownian(c, 1);
-    for(int i=0; i<c->type; i++) if(passable(c->move(i), c, P_MONSTER | P_MIRROR | P_CLIMBUP | P_CLIMBDOWN)) {
-      destroyHalfvine(c->move(i));
-      minerEffect(c->move(i));
-      brownian::dissolve_brownian(c->move(i), 1);
-      if(c->move(i)->monst == moSlime || c->move(i)->monst == moSlimeNextTurn)
-        killMonster(c->move(i), who);
+    forCellEx(c1, c) if(passable(c1, c, P_MONSTER | P_MIRROR | P_CLIMBUP | P_CLIMBDOWN)) {
+      changes.ccell(c1);
+      destroyHalfvine(c1);
+      minerEffect(c1);
+      brownian::dissolve_brownian(c1, 1);
+      if(c1->monst == moSlime || c1->monst == moSlimeNextTurn)
+        killMonster(c1, who);
       }
     forCellEx(c2, c) {
+      changes.ccell(c2);
       if(c2->wall == waPalace) c2->wall = waRubble;
       if(c2->wall == waDeadwall) c2->wall = waDeadfloor2;
       if(c2->wall == waExplosiveBarrel) explodeBarrel(c2);
@@ -716,12 +733,13 @@ EX void killMonster(cell *c, eMonster who, flagtype deathflags IS(0)) {
       degradeDemons();
       }
     }
-  if(isIvy(c)) {
+  if(isIvy(c)) {    
     pcount = 0;
     eMonster m = c->monst;
     bignum s = ivy_total() - 1;
     /*if((m == moIvyBranch || m == moIvyHead) && c->move(c->mondir)->monst == moIvyRoot)
       ivynext(c, moIvyNext); */
+    changes.value_keep(clearing::imputed);
     killIvy(c, who);
     s = ivy_total() - s;
     if(s > bignum(1) && vid.bubbles_special)
@@ -759,6 +777,7 @@ EX void killMonster(cell *c, eMonster who, flagtype deathflags IS(0)) {
     useupOrb(itOrbLuck, items[itOrbLuck] / 2);
   
   if(m == moAirElemental) {
+    changes.value_keep(airmap);
     airmap.clear();
     for(int i=0; i<isize(dcal); i++)
       if(dcal[i]->monst == moAirElemental)
@@ -1033,7 +1052,7 @@ EX bool flashWouldKill(cell *c, flagtype extra) {
       cell *c3 = c2->move(u);
       if(isWorm(c3)) continue; // immune to Flash
       if(c3->monst == moEvilGolem) continue; // evil golems don't count
-      if(c3 != c && (c3->monst || isPlayerOn(c3)) && !stalemate::isKilled(c3)) {
+      if(c3 != c && (c3->monst || isPlayerOn(c3))) {
         bool b = canAttack(NULL, moWitchFlash, c3, c3->monst, AF_MAGIC | extra);
         if(b) return true;
         }
diff --git a/basegraph.cpp b/basegraph.cpp
index e8c47bc8..791279ff 100644
--- a/basegraph.cpp
+++ b/basegraph.cpp
@@ -816,6 +816,7 @@ void addMessageToLog(msginfo& m, vector<msginfo>& log) {
 EX void clearMessages() { msgs.clear(); }
 
 EX void addMessage(string s, char spamtype) {
+  LATE( addMessage(s, spamtype); )
   DEBB(DF_MSG, ("addMessage: ", s));
 
   msginfo m;
diff --git a/checkmove.cpp b/checkmove.cpp
index bad4217f..5aa3756f 100644
--- a/checkmove.cpp
+++ b/checkmove.cpp
@@ -42,79 +42,13 @@ EX bool hasSafeOrb(cell *c) {
 struct stalemate1 {
   eMonster who;
   cell *moveto;
-  cell *killed;
   cell *pushto;
   cell *comefrom;
   cell *swordlast[2], *swordtransit[2], *swordnext[2];
-  bool isKilled(cell *c);
-  stalemate1(eMonster w, cell *mt, cell *ki, cell *pt, cell *cf) : who(w), moveto(mt), killed(ki), pushto(pt), comefrom(cf) {}
+  stalemate1(eMonster w, cell *mt, cell *pt, cell *cf) : who(w), moveto(mt), pushto(pt), comefrom(cf) {}
   };
 #endif
 
-EX bool used_impact;
-
-bool stalemate1::isKilled(cell *w) {
-  if(w->monst == moNone || w == killed) return true;
-  if(!moveto) return false;
-  
-  for(int b=0; b<2; b++) 
-    if((w == swordnext[b] || w == swordtransit[b]) && canAttack(moveto, who, w, w->monst, AF_SWORD))
-      return true;
-  
-  if(logical_adjacent(moveto, who, w) && moveto != comefrom) {
-    int wid = neighborId(moveto, w);
-    int wfrom = neighborId(moveto, comefrom);
-    int flag = AF_APPROACH;
-    if(wid >= 0 && wfrom >= 0 && anglestraight(moveto, wfrom, wid)) flag |= AF_HORNS;
-    if(canAttack(moveto, who, w, w->monst, flag)) return true;
-    }
-  
-  if(used_impact && !isMultitile(w) && isNeighbor(w, moveto))
-    return true;
-
-  if(isNeighbor(w, comefrom) && comefrom == moveto && killed) {
-    int d1 = neighborId(comefrom, w);
-    int d2 = neighborId(comefrom, killed);
-    int di = angledist(comefrom->type, d1, d2);
-    if(di && items[itOrbSide1-1+di] && canAttack(moveto, who, w, w->monst, AF_SIDE))
-      return true;
-    }
-
-  if(logical_adjacent(comefrom, who, w) && logical_adjacent(moveto, who, w) && moveto != comefrom)
-    if(canAttack(moveto, who, w, w->monst, AF_STAB))
-      return true;
-
-  if(who == moPlayer && (killed || moveto != comefrom) && mirror::isKilledByMirror(w)) return true;
-  if(w->monst == moIvyHead || w->monst == moIvyBranch || isMutantIvy(w))
-    return isChild(w, killed);
-
-  if(isDragon(w->monst) && killed && isDragon(killed->monst) && killed->hitpoints) {
-    cell *head1 = dragon::findhead(w);
-    cell *head2 = dragon::findhead(killed);
-    if(head1 == head2 && dragon::totalhp(head1) ==1) return true;
-    }
-  
-  if((w->monst == moPair || isMagneticPole(w->monst)) && killed && w->move(w->mondir) == killed)
-    return true;
-  
-  if(w->monst == moKrakenT && killed && killed->monst == moKrakenT && killed->hitpoints) {
-    cell *head1 = w->move(w->mondir);
-    cell *head2 = killed->move(killed->mondir);
-    if(head1 == head2 && kraken::totalhp(head1) == 1) return true;
-    }
-  
-  return false;
-  }
-
-EX namespace stalemate {
-  EX bool isKilled(cell *w) {
-    for(int f=0; f<isize(moves); f++)
-      if(moves[f].isKilled(w)) return true;
-    
-    return false;
-    };
-EX }
-
 EX bool krakensafe(cell *c) {
   return items[itOrbFish] || items[itOrbAether] || 
     (c->item == itOrbFish && c->wall == waBoat) || 
@@ -149,7 +83,7 @@ EX bool monstersnear(stalemate1& sm) {
   
   if(havewhat&HF_OUTLAW) {
     for(cell *c1: gun_targets(c)) 
-      if(c1->monst == moOutlaw && !c1->stuntime && !stalemate::isKilled(c1)) {
+      if(c1->monst == moOutlaw && !c1->stuntime) {
         res++; who_kills_me = moOutlaw;
         }
     }
@@ -166,7 +100,7 @@ EX bool monstersnear(stalemate1& sm) {
       if(c3->monst != moWitchFlash)
         if(!logical_adjacent(c3, c3->monst, c2) || !logical_adjacent(c2, c3->monst, c))
           continue;
-      if(elec::affected(c3) || stalemate::isKilled(c3)) continue;
+      if(elec::affected(c3)) continue;
       if(c3->stuntime > (sm.who == moPlayer ? 0 : 1)) continue;
       // speedwitches can only attack not-fastened monsters,
       // others can only attack if the move is not fastened
@@ -174,7 +108,7 @@ EX bool monstersnear(stalemate1& sm) {
       if(c3->monst != moWitchSpeed && fast) continue;
       // cannot attack if the immediate cell is impassable (except flashwitches)
       if(c3->monst != moWitchFlash) {
-        if(!passable(c2, c3, stalemate::isKilled(c2)?P_MONSTER:0)) continue;
+        if(!passable(c2, c3, 0)) continue;
         if(isPlayerOn(c2) && items[itOrbFire]) continue;
         }
       // flashwitches cannot attack if it would kill another enemy
@@ -185,7 +119,6 @@ EX bool monstersnear(stalemate1& sm) {
     // consider normal monsters
     if(c2 && 
       isArmedEnemy(c2, sm.who) && 
-      !stalemate::isKilled(c2) &&
       (c2->monst != moLancer || isUnarmed(sm.who) || !logical_adjacent(c, sm.who, c2))) {
       eMonster m = c2->monst;
       if(elec::affected(c2)) continue;
@@ -267,11 +200,11 @@ EX bool monstersnear2() {
   return b;
   }
 
-EX bool monstersnear(cell *c, cell *nocount, eMonster who, cell *pushto, cell *comefrom) {
+EX bool monstersnear(cell *c, eMonster who, cell *pushto, cell *comefrom) {
 
   if(peace::on) return 0; // you are safe
 
-  stalemate1 sm(who, c, nocount, pushto, comefrom);
+  stalemate1 sm(who, c, pushto, comefrom);
   
   if(who == moPlayer) for(int b=0; b<2; b++) sm.swordlast[b] = sword::pos(multi::cpid, b);
   
@@ -340,11 +273,6 @@ EX namespace stalemate {
     return false;
     }
 
-  EX bool isKilledDirectlyAt(cell *c) {
-    for(int i=0; i<isize(moves); i++) if(moves[i].killed == c) return true;
-    return false;
-    }
-  
   EX bool isPushto(cell *c) {
     for(int i=0; i<isize(moves); i++) if(moves[i].pushto == c) return true;
     return false;
diff --git a/complex.cpp b/complex.cpp
index 60b7582b..e3d95b28 100644
--- a/complex.cpp
+++ b/complex.cpp
@@ -221,7 +221,7 @@ EX namespace elec {
     if(c->wall == waChasm)
       return ecIsolator;
 
-    if(shmup::on ? isPlayerOn(c) : (isPlayerOn(c) || stalemate::isMoveto(c) || (items[itOrbEmpathy] && isFriendly(c)))) {
+    if(shmup::on ? isPlayerOn(c) : (isPlayerOn(c) || (items[itOrbEmpathy] && isFriendly(c)))) {
       if(items[itOrbShield]) return ecIsolator;
       if(afterOrb) return ecIsolator;
       if(!items[itOrbAether]) return isElectricLand(c) ? ecConductor : ecGrounded;
@@ -229,12 +229,8 @@ EX namespace elec {
     
     // if(c->monst && stalemate::moveto) printf("%p: isKilled = %d\n", c, stalemate::isKilled(c));
 
-    else if(
-      (c->monst || stalemate::isPushto(c))
-      && 
-      (stalemate::isPushto(c) || !stalemate::isKilled(c)) 
-      && 
-      c->monst != moGhost && c->monst != moIvyDead && c->monst != moIvyNext 
+    else if(c->monst 
+      && c->monst != moGhost && c->monst != moIvyDead && c->monst != moIvyNext 
       && !(isDragon(c->monst) && !c->hitpoints)
       )
       return isElectricLand(c) ? (ao ? ecCharged : ecConductor) : ecGrounded;
@@ -473,6 +469,7 @@ EX namespace elec {
   // 0 = no close escape, 1 = close escape, 2 = message already shown
   EX int lightningfast;
   EX void checklightningfast() {
+    changes.value_keep(lightningfast);
     if(lightningfast == 1) {
       addMessage(XLAT("Wow! That was close."));
       lightningfast = 2;
@@ -700,6 +697,7 @@ struct info {
     eMonster m = c->monst;
   
     static int msgid = 0;
+    changes.value_keep(msgid);
   
     playSound(c, princessgender() ? "speak-princess" : "speak-prince");
     retry:
@@ -990,8 +988,10 @@ EX namespace clearing {
   EX void imput(cell *c) {
     if(bounded) return;
     if(score.count(c)) return;
+    changes.map_value(score, c);
     auto& is = score[c];
     celltype t = get_celltype(c);
+    changes.map_value(stats, t);
     auto& stat = stats[t];
     is.second = c->mondir;
     if(c->mpdist <= 6) {
@@ -1413,10 +1413,12 @@ EX namespace mirror {
       bool survive = true;
       if(m.first == multi::cpid) {
         cell *c = m.second.at;
+        changes.ccell(c);
         if(!m.second.mirrored) nummirage++;
         auto cw2 = m.second + wstep;
         if(inmirror(cw2)) cw2 = reflect(cw2);
         cell *c2 = cw2.at;
+        changes.ccell(c2);
         if(c2->monst) {
           c->monst = moMimic;
           eMonster m2 = c2->monst;
@@ -1453,6 +1455,7 @@ EX namespace mirror {
     }
 
   EX void act(int d, int flags) {
+    changes.value_keep(mirrors);
     destroyKilled();
     unlist();
     if(multi::players == 1) multi::cpid = 0;
@@ -1469,6 +1472,7 @@ EX namespace mirror {
     }
   
   EX void breakAll() {
+    changes.value_keep(mirrors);
     destroyKilled();
     unlist();
     if(numplayers() == 1)
@@ -2619,6 +2623,7 @@ EX namespace dragon {
     int penalty = 0;
     int maxlen = 1000;
     while(maxlen-->0) {
+      changes.ccell(c);
       makeflame(c, 5, false);
       eMonster m = c->monst;
       drawFireParticles(c, 16);
@@ -2879,24 +2884,25 @@ EX namespace kraken {
     if(c->land == laKraken && !c->item) c->item = itKraken;
     kills[moKrakenH]++;
     if(checkOrb(who, itOrbStone)) c->wall = waNone;
-    for(int i=0; i<c->type; i++)
-      if(c->move(i)->monst == moKrakenT) {
+    forCellEx(c1, c) 
+      if(c1->monst == moKrakenT) {
+        changes.ccell(c1);        
         drawParticles(c, minf[moKrakenT].color, 16);
-        c->move(i)->monst = moNone;
+        c1->monst = moNone;
         if(checkOrb(who, itOrbStone)) {
-          if(isWatery(c->move(i)))
-            c->move(i)->wall = waNone;
+          if(isWatery(c1))
+            c1->wall = waNone;
           else
-            c->move(i)->wall = waPetrified, c->move(i)->wparam = moKrakenT;
+            c1->wall = waPetrified, c1->wparam = moKrakenT;
           }
         }
     }
   
   EX int totalhp(cell *c) {
     int total = 0;
-    for(int i=0; i<c->type; i++)
-      if(c->move(i)->monst == moKrakenT)
-        total += c->move(i)->hitpoints;
+    forCellEx(c1, c)
+      if(c1->monst == moKrakenT)
+        total += c1->hitpoints;
     return total;
     }
   
@@ -3616,6 +3622,7 @@ EX namespace halloween {
   
   void putMonster(eMonster m) {
     cell *c = farempty();
+    changes.ccell(c);
     c->hitpoints = 3;
     c->monst = m;
     playSeenSound(c);
@@ -3655,6 +3662,10 @@ EX namespace halloween {
     farempty()->item = itTreat;
     int itr = items[itTreat];
     items[itOrbTime] += 30;
+    changes.value_keep(dragoncount);
+    changes.value_keep(demoncount);
+    changes.value_keep(swordpower);
+
     int monpower = 19 + itr + hrand(itr);
     int mcount = 0;
     while(monpower > 0) {
diff --git a/complex2.cpp b/complex2.cpp
index 5d3cb90c..e31491ad 100644
--- a/complex2.cpp
+++ b/complex2.cpp
@@ -378,6 +378,7 @@ EX void knightFlavorMessage(cell *c2) {
   bool tooeasy = (rad < newRoundTableRadius());
 
   static int msgid = 0;
+  changes.value_keep(msgid);
 
   retry:
   if(msgid >= 32) msgid = 0;  
diff --git a/environment.cpp b/environment.cpp
index f1ed3d29..da93956f 100644
--- a/environment.cpp
+++ b/environment.cpp
@@ -358,7 +358,7 @@ EX void bfs() {
         if(c2->monst) {
           if(isHaunted(c2->land) && 
             c2->monst != moGhost && c2->monst != moZombie && c2->monst != moNecromancer)
-            survivalist = false;
+            fail_survivalist();
           if(c2->monst == moHexSnake || c2->monst == moHexSnakeTail) {
             havewhat |= HF_HEX;
             if(c2->mondir != NODIR)
@@ -753,6 +753,7 @@ EX void monstersTurn() {
   if(!phase1) heat::processfires();
   
   for(cell *c: crush_now) {
+    changes.ccell(c);
     playSound(NULL, "closegate");
     if(canAttack(c, moCrusher, c, c->monst, AF_GETPLAYER | AF_CRUSH)) {
       attackMonster(c, AF_MSG | AF_GETPLAYER | AF_CRUSH, moCrusher);
@@ -762,6 +763,8 @@ EX void monstersTurn() {
     explodeBarrel(c);
     }
   
+  changes.value_keep(crush_now);
+  changes.value_keep(crush_next);
   crush_now = move(crush_next);
   crush_next.clear();
   
diff --git a/graph.cpp b/graph.cpp
index 0a1d15ce..6657789b 100644
--- a/graph.cpp
+++ b/graph.cpp
@@ -3875,6 +3875,7 @@ struct flashdata {
 vector<flashdata> flashes;
 
 EX void drawBubble(cell *c, color_t col, string s, ld size) {
+  LATE( drawBubble(c, col, s, size); )
   auto fd = flashdata(ticks, 1000, c, col, 0);
   fd.text = s;
   fd.angle = size;
@@ -3889,6 +3890,7 @@ EX void drawBigFlash(cell *c) {
   }
 
 EX void drawParticleSpeed(cell *c, color_t col, int speed) {
+  LATE( drawParticleSpeed(c, col, speed); )
   if(vid.particles && !confusingGeometry())
     flashes.push_back(flashdata(ticks, rand() % 16, c, col, speed)); 
   }
@@ -3906,6 +3908,7 @@ EX void drawFireParticles(cell *c, int qty, int maxspeed IS(100)) {
   }
 EX void fallingFloorAnimation(cell *c, eWall w IS(waNone), eMonster m IS(moNone)) {
   if(!wmspatial) return;
+  LATE( fallingFloorAnimation(c, w, m); )
   fallanim& fa = fallanims[c];
   fa.t_floor = ticks;
   fa.walltype = w; fa.m = m;
@@ -3913,6 +3916,7 @@ EX void fallingFloorAnimation(cell *c, eWall w IS(waNone), eMonster m IS(moNone)
   }
 EX void fallingMonsterAnimation(cell *c, eMonster m, int id IS(multi::cpid)) {
   if(!mmspatial) return;
+  LATE( fallingMonsterAnimation(c, m, id); )
   fallanim& fa = fallanims[c];
   fa.t_mon = ticks;
   fa.m = m;
@@ -5167,6 +5171,7 @@ EX transmatrix iadj(const movei& m) {
 
 EX void animateMovement(const movei& m, int layer) {
   if(vid.mspeed >= 5) return; // no animations!
+  LATE ( animateMovement(m, layer); )
   transmatrix T = iadj(m);
   bool found_s = animations[layer].count(m.s);
   animation& a = animations[layer][m.t];
@@ -5187,6 +5192,7 @@ EX void animateMovement(const movei& m, int layer) {
   }
 
 EX void animateAttack(const movei& m, int layer) {
+  LATE( animateAttack(m, layer); )
   if(vid.mspeed >= 5) return; // no animations!
   transmatrix T = iadj(m);
   bool newanim = !animations[layer].count(m.s);
@@ -5200,6 +5206,7 @@ vector<pair<cell*, animation> > animstack;
 
 EX void indAnimateMovement(const movei& m, int layer) {
   if(vid.mspeed >= 5) return; // no animations!
+  LATE( indAnimateMovement(m, layer); )
   if(animations[layer].count(m.t)) {
     animation res = animations[layer][m.t];
     animations[layer].erase(m.t);
@@ -5218,6 +5225,7 @@ EX void indAnimateMovement(const movei& m, int layer) {
   }
 
 EX void commitAnimations(int layer) {
+  LATE( commitAnimations(layer); )
   for(int i=0; i<isize(animstack); i++)
     animations[layer][animstack[i].first] = animstack[i].second;
   animstack.clear();
diff --git a/hyper.h b/hyper.h
index 903c6016..987f621e 100644
--- a/hyper.h
+++ b/hyper.h
@@ -777,6 +777,10 @@ static inline void set_flag(flagtype& f, flagtype which, bool b) {
 
 }
 
+/** this macro is used to delay performing the action in case if everything is rolled back */
+#define LATE(x) \
+  if(changes.on) { changes.at_commit([=] { x; }); return; }
+
 // assert macro
 #ifdef NDEBUG
 #define hassert(condition) if(!condition) __builtin_unreachable()
diff --git a/items.cpp b/items.cpp
index 4ef2874c..57ef6436 100644
--- a/items.cpp
+++ b/items.cpp
@@ -146,11 +146,12 @@ EX bool collectItem(cell *c2, bool telekinesis IS(false)) {
     babymap.erase(c2);
     int bold = seekbits;
     seekbits = bnew;
-    tortoise::last = seekbits;
+    changes.value_set(tortoise::last, seekbits);
     if(seek()) {
       cell *c = passable(cwt.at, NULL, 0) ? cwt.at : c2;
       c->item = itBabyTortoise;
       if(c == c2) dopickup = false;
+      changes.map_value(babymap, c);
       babymap[c] = bold;
       }
     else items[itBabyTortoise]++;
@@ -289,7 +290,8 @@ EX void dropGreenStone(cell *c) {
     else {
       c->item = itGreenStone;
       addMessage(XLAT("You drop %the1.", itGreenStone));
-      if(isHaunted(cwt.at->land)) survivalist = false;
+      if(isHaunted(cwt.at->land)) 
+        fail_survivalist();
       }
     }
   else {
@@ -402,7 +404,8 @@ EX int maxgold() {
 
 EX void updateHi(eItem it, int v) {
   if(!yendor::on)
-    if(v > hiitems[modecode()][it]) hiitems[modecode()][it] = v;
+    if(v > hiitems[modecode()][it]) 
+      changes.value_set(hiitems[modecode()][it], v);
   }
 
 EX void gainItem(eItem it) {
diff --git a/mapeffects.cpp b/mapeffects.cpp
index 1a2872cb..a074eb4d 100644
--- a/mapeffects.cpp
+++ b/mapeffects.cpp
@@ -8,9 +8,6 @@
 #include "hyper.h"
 namespace hr {
 
-/** offscreen cells to take care off */
-EX vector<cell*> offscreen;
-
 EX void initcell(cell *c) {
   c->mpdist = INFD;   // minimum distance from the player, ever
   c->cpdist = INFD;   // current distance from the player
diff --git a/monstermove.cpp b/monstermove.cpp
index bc5734d8..2496cfd7 100644
--- a/monstermove.cpp
+++ b/monstermove.cpp
@@ -85,11 +85,15 @@ EX void moveEffect(const movei& mi, eMonster m) {
   if(cf && isPrincess(m)) princess::move(mi);
   
   if(cf && m == moTortoise) {
+    changes.map_value(tortoise::emap, ct);
+    changes.map_value(tortoise::emap, cf);
     tortoise::emap[ct] = tortoise::getb(cf);
     tortoise::emap.erase(cf);
     }
   
   if(cf && ct->item == itBabyTortoise && !cf->item) {
+    changes.map_value(tortoise::babymap, ct);
+    changes.map_value(tortoise::babymap, cf);
     cf->item = itBabyTortoise;
     ct->item = itNone;
     animateMovement(mi.rev(), LAYER_BOAT);
@@ -1520,7 +1524,7 @@ EX int movevalue(eMonster m, cell *c, cell *c2, flagtype flags) {
     isInactiveEnemy(c2,m) ? 1000 :
     -500;
 
-  else if(monstersnear(c2, NULL, m, NULL, c)) val = 50; // linked with mouse suicide!
+  else if(monstersnear(c2, m, NULL, c)) val = 50; // linked with mouse suicide!
   else if(passable_for(m, c2, c, 0)) {
     if(mine::marked_mine(c2) && !ignoresPlates(m))
       val = 50;
diff --git a/orbs.cpp b/orbs.cpp
index d0a62211..de9a570d 100644
--- a/orbs.cpp
+++ b/orbs.cpp
@@ -78,7 +78,8 @@ EX int intensify(int val) {
 EX bool reduceOrbPower(eItem it, int cap) {
   if(items[it] && (lastorbused[it] || (it == itOrbShield && items[it]>3) || !markOrb(itOrbTime))) {
     items[it] -= multi::activePlayers();
-    if(isHaunted(cwt.at->land)) survivalist = false;
+    if(isHaunted(cwt.at->land)) 
+      fail_survivalist();
     if(items[it] < 0) items[it] = 0;
     if(items[it] > cap && markOrb(itOrbIntensity)) cap = intensify(cap);
     if(items[it] > cap && timerghost) items[it] = cap;
@@ -589,7 +590,7 @@ void teleportTo(cell *dest) {
   mine::auto_teleport_charges();
   }
 
-EX void jumpTo(cell *dest, eItem byWhat, int bonuskill IS(0), eMonster dashmon IS(moNone)) {
+EX bool jumpTo(orbAction a, cell *dest, eItem byWhat, int bonuskill IS(0), eMonster dashmon IS(moNone)) {
   if(byWhat != itStrongWind) playSound(dest, "orb-frog");
   cell *from = cwt.at;
 
@@ -620,6 +621,17 @@ EX void jumpTo(cell *dest, eItem byWhat, int bonuskill IS(0), eMonster dashmon I
     cwt.spin = i;
     flipplayer = true;
     }
+
+  if(!monstersnearO(a, dest, moPlayer, NULL, cwt.at)) {
+    changes.rollback();
+    return false;
+    }
+  
+  if(isCheck(a)) {
+    changes.rollback();
+    return true;
+    }
+
   countLocalTreasure();
   
   sword::reset();
@@ -650,6 +662,8 @@ EX void jumpTo(cell *dest, eItem byWhat, int bonuskill IS(0), eMonster dashmon I
     shmup::teleported();
   else
     monstersTurn();
+
+  return true;
   }
 
 void growIvyTo(const movei& mi) {
@@ -1019,18 +1033,13 @@ void useOrbOfDragon(cell *c) {
   checkmoveO();
   }
 
-bool monstersnearO(orbAction a, cell *c, cell *nocount, eMonster who, cell *pushto, cell *comefrom) {
+EX bool monstersnearO(orbAction a, cell *c, eMonster who, cell *pushto, cell *comefrom) {
   // printf("[a = %d] ", a);
   if(shmup::on) return false;
   if(a == roCheck && multi::players > 1) 
     return true;
   else if(a == roMultiCheck) return false;
-  else return monstersnear(c, nocount, who, pushto, comefrom);
-  }
-
-bool monstersnearOS(orbAction a, cell *c, cell *nocount, eMonster who, cell *pushto, cell *comefrom) {
-  dynamicval<bool> b(used_impact, items[itOrbImpact]);
-  return monstersnearO(a, c, nocount, who, pushto, comefrom);
+  else return monstersnear(c, who, pushto, comefrom);
   }
 
 EX bool isCheck(orbAction a) { return a == roCheck || a == roMultiCheck; }
@@ -1149,9 +1158,9 @@ EX eItem targetRangedOrb(cell *c, orbAction a) {
     }
   
   // (0-) strong wind
-  if(items[itStrongWind] && c->cpdist == 2 && cwt.at == whirlwind::jumpFromWhereTo(c, true) && !monstersnearO(a, c, NULL, moPlayer, NULL, cwt.at)) {
-    if(!isCheck(a)) jumpTo(c, itStrongWind);
-    return itStrongWind;
+  if(items[itStrongWind] && c->cpdist == 2 && cwt.at == whirlwind::jumpFromWhereTo(c, true)) {
+    changes.init();
+    if(jumpTo(a, c, itStrongWind)) return itStrongWind;
     }
   
   // (0x) control
@@ -1195,12 +1204,12 @@ EX eItem targetRangedOrb(cell *c, orbAction a) {
 
         if(c->monst) {
           if(!canAttack(cf, moFriendlyIvy, c, c->monst, 0)) continue;
-          if(monstersnear(cwt.at, c, moPlayer, NULL, cwt.at)) continue;
+          if(monstersnear(cwt.at, moPlayer, NULL, cwt.at)) continue;
           }
         else {
           if(!passable(c, cf, P_ISPLAYER | P_MONSTER)) continue;
           if(strictlyAgainstGravity(c, cf, false, MF_IVY)) continue;
-          if(monstersnear(cwt.at, NULL, moPlayer, c, cwt.at)) continue;
+          if(monstersnear(cwt.at, moPlayer, c, cwt.at)) continue;
           }
         dirs.push_back(d);
         }
@@ -1223,22 +1232,19 @@ EX eItem targetRangedOrb(cell *c, orbAction a) {
     jumpstate = 10 + check_vault(cwt.at, c, P_ISPLAYER, jumpthru);
     items[itOrbAether] = i;
 
-    if(jumpstate == 16 && !monstersnearOS(a, c, jumpthru, moPlayer, NULL, cwt.at)) jumpstate = 17;
-    
-    if(jumpstate == 17) {
-      if(!isCheck(a)) {
-        int k = tkills();
-        eMonster m = jumpthru->monst;
-        if(jumpthru->wall == waShrub) {
-          addMessage(XLAT("You chop down the shrub."));
-          jumpthru->wall = waNone;
-          }
-        if(m)
-          attackMonster(jumpthru, AF_NORMAL | AF_MSG, moPlayer);
-        k = tkills() - k;
-        jumpTo(c, itOrbDash, k, m);
+    if(jumpstate == 15) {
+      changes.init();
+      int k = tkills();
+      eMonster m = jumpthru->monst;
+      if(jumpthru->wall == waShrub) {
+        addMessage(XLAT("You chop down the shrub."));
+        jumpthru->wall = waNone;
         }
-      return itOrbDash;
+      if(m)
+        attackMonster(jumpthru, AF_NORMAL | AF_MSG, moPlayer);
+      k = tkills() - k;
+      if(jumpTo(a, c, itOrbDash, k, m)) jumpstate = 16;
+      if(jumpstate == 16) return itOrbDash;
       }
     }
   
@@ -1247,10 +1253,10 @@ EX eItem targetRangedOrb(cell *c, orbAction a) {
     if(i) items[itOrbAether] = i-1;
     jumpstate = check_jump(cwt.at, c, P_ISPLAYER, jumpthru);
     items[itOrbAether] = i;
-    if(jumpstate == 3 && !monstersnearOS(a, c, NULL, moPlayer, NULL, cwt.at)) {
-      jumpstate = 4;
-      if(!isCheck(a)) jumpTo(c, itOrbFrog);
-      return itOrbFrog;
+    if(jumpstate == 3) {
+      changes.init();
+      if(jumpTo(a, c, itOrbFrog)) jumpstate = 4;
+      if(jumpstate == 4) return itOrbFrog;
       }
     }
   
@@ -1260,9 +1266,9 @@ EX eItem targetRangedOrb(cell *c, orbAction a) {
     if(i) items[itOrbAether] = i-1;
     jumpstate = 20 + check_phase(cwt.at, c, P_ISPLAYER, jumpthru);
     items[itOrbAether] = i;
-    if(jumpstate == 23 && !monstersnearOS(a, c, NULL, moPlayer, NULL, cwt.at)) {
-      jumpstate = 24;
-      if(!isCheck(a)) jumpTo(c, itOrbPhasing);
+    if(jumpstate == 23) {
+      changes.init();
+      if(jumpTo(a, c, itOrbPhasing)) jumpstate = 24;
       }
     if(shmup::on) shmup::popmonsters();
     if(jumpstate == 24) return itOrbPhasing;
@@ -1302,9 +1308,16 @@ EX eItem targetRangedOrb(cell *c, orbAction a) {
   if(!shmup::on && items[itRevolver] && c->monst && canAttack(cwt.at, moPlayer, c, c->monst, AF_GUN)) {
     bool inrange = false;
     for(cell *c1: gun_targets(cwt.at)) if(c1 == c) inrange = true;
-    if(inrange && !monstersnearOS(a, cwt.at, c, moPlayer, NULL, cwt.at)) {
-      if(!isCheck(a)) gun_attack(c), apply_impact(c);
-      return itRevolver;
+    if(inrange) {
+      changes.init();
+      gun_attack(c), apply_impact(c);
+      if(monstersnearO(a, cwt.at, moPlayer, NULL, cwt.at)) {
+        changes.rollback();
+        }
+      else {
+        if(isCheck(a)) changes.rollback();
+        return itRevolver;
+        }
       }
     }
   
diff --git a/pcmove.cpp b/pcmove.cpp
index 33105a20..1416715f 100644
--- a/pcmove.cpp
+++ b/pcmove.cpp
@@ -19,6 +19,10 @@ EX bool hauntedWarning;
 /** is the Survivalist achievement still valid? have we received it? */
 EX bool survivalist, got_survivalist;
 
+EX void fail_survivalist() {
+  changes.value_set(survivalist, false);
+  }
+
 /** last move was invisible */
 EX bool invismove = false;
 /** last move was invisible due to Orb of Fish (thus Fish still see you)*/
@@ -113,7 +117,6 @@ EX bool checkNeedMove(bool checkonly, bool attacking) {
     return false;
   int flags = 0;
   if(cwt.at->monst) {
-    if(checkonly) return true;
     if(isMountable(cwt.at->monst))
       addMessage(XLAT("You need to dismount %the1!", cwt.at->monst));
     else
@@ -128,13 +131,11 @@ EX bool checkNeedMove(bool checkonly, bool attacking) {
     if(markOrb2(itOrbAether)) return false;
     if(markOrb2(itOrbFish)) return false;
     if(in_gravity_zone(cwt.at) && passable(cwt.at, NULL, P_ISPLAYER)) return false;
-    if(checkonly) return true;
     flags |= AF_FALL;
     addMessage(XLAT("Ice below you is melting! RUN!"));
     }
   else if(!attacking && cellEdgeUnstable(cwt.at)) {
     if(markOrb2(itOrbAether)) return false;
-    if(checkonly) return true;
     if(in_gravity_zone(cwt.at) && passable(cwt.at, NULL, P_ISPLAYER)) return false;
     addMessage(XLAT("Nothing to stand on here!"));
     }
@@ -142,29 +143,24 @@ EX bool checkNeedMove(bool checkonly, bool attacking) {
     if(markOrb(itOrbFish)) return false;
     if(markOrb2(itOrbAether)) return false;
     if(in_gravity_zone(cwt.at) && passable(cwt.at, NULL, P_ISPLAYER)) return false;
-    if(checkonly) return true;
     addMessage(XLAT("You have to run away from the water!"));
     }
   else if(cwt.at->wall == waClosedGate) {
     if(markOrb2(itOrbAether)) return false;
-    if(checkonly) return true;
     addMessage(XLAT("The gate is closing right on you! RUN!"));
     }
   else if(isFire(cwt.at) && !markOrb(itOrbWinter) && !markOrb2(itOrbShield)) {
     if(markOrb2(itOrbAether)) return false;
-    if(checkonly) return true;
     addMessage(XLAT("This spot will be burning soon! RUN!"));
     }
   else if(cwt.at->wall == waMagma && !markOrb(itOrbWinter) && !markOrb2(itOrbShield)) {
     if(markOrb2(itOrbAether)) return false;
     if(in_gravity_zone(cwt.at) && passable(cwt.at, cwt.at, P_ISPLAYER)) return false;
-    if(checkonly) return true;
     addMessage(XLAT("Run away from the magma!"));
     }
   else if(cwt.at->wall == waChasm) {
     if(markOrb2(itOrbAether)) return false;
     if(in_gravity_zone(cwt.at) && passable(cwt.at, cwt.at, P_ISPLAYER)) return false;
-    if(checkonly) return true;
     flags |= AF_FALL;
     addMessage(XLAT("The floor has collapsed! RUN!"));
     }
@@ -175,7 +171,6 @@ EX bool checkNeedMove(bool checkonly, bool attacking) {
   else if(!passable(cwt.at, NULL, P_ISPLAYER)) {
     if(isFire(cwt.at)) return false; // already checked: have Shield
     if(markOrb2(itOrbAether)) return false;
-    if(checkonly) return true;
     addMessage(XLAT("Your Aether power has expired! RUN!"));
     }
   else return false;
@@ -260,7 +255,7 @@ bool pcmove::movepcto() {
     lastmountpos[0] = cwt.at;
   
   if(againstRose(cwt.at, NULL) && d<0 && !scentResistant()) {
-    if(!checkonly) addMessage("You just cannot stand in place, those roses smell too nicely.");
+    addMessage("You just cannot stand in place, those roses smell too nicely.");
     return false;
     }
 
@@ -270,7 +265,16 @@ bool pcmove::movepcto() {
   fmsAttack   = forcedmovetype == fmSkip || forcedmovetype == fmAttack;
   fmsActivate = forcedmovetype == fmSkip || forcedmovetype == fmActivate;
   
-  return (d >= 0) ? actual_move() : stay();
+  changes.init();
+  bool b = (d >= 0) ? actual_move() : stay();
+  if(checkonly || !b) {
+    changes.rollback();
+    }
+  else if(changes.on) {
+    println(hlog, "error: not commited!");
+    changes.commit();
+    }
+  return b;
   }
 
 bool pcmove::after_move() {
@@ -294,17 +298,17 @@ bool pcmove::after_move() {
   check_total_victory();
 
   if(items[itWhirlpool] && cwt.at->land != laWhirlpool && !whirlpool::escaped) {
-    whirlpool::escaped = true;
+    changes.value_set(whirlpool::escaped, true);
     achievement_gain("WHIRL1");
     }
 
   if(items[itLotus] >= 25 && !isHaunted(cwt.at->land) && survivalist && !got_survivalist) {
-    got_survivalist = true;
+    changes.value_set(got_survivalist, true);
     achievement_gain("SURVIVAL");
     }
 
   if(seenSevenMines && cwt.at->land != laMinefield) {
-    seenSevenMines = false;
+    changes.value_set(seenSevenMines, false);
     achievement_gain("SEVENMINE");
     }
   
@@ -314,11 +318,21 @@ bool pcmove::after_move() {
 
 bool pcmove::swing() {
   sideAttack(cwt.at, d, moPlayer, 0);
-  animateAttack(mi, LAYER_SMALL);
 
+  mirror::act(origd, mirror::SPINMULTI | mirror::ATTACK);
+
+  if(monstersnear(cwt.at, moPlayer, nullptr, cwt.at)) {
+    changes.rollback();
+    if(errormsgs && !checkonly)
+      wouldkill("You would be killed by %the1!");          
+    return false;
+    }
+  if(checkonly) return true;
+  if(changes.on) changes.commit();
+
+  animateAttack(mi, LAYER_SMALL);
   if(survivalist && isHaunted(mi.t->land))
     survivalist = false;
-  mirror::act(origd, mirror::SPINMULTI | mirror::ATTACK);
   lastmovetype = lmTree; lastmove = mi.t;
   swordAttackStatic();
 
@@ -334,72 +348,129 @@ bool pcmove::after_instant(bool kl) {
   return true;
   }
 
-struct chaos_data {
-  cell *ca, *cb;
-  gcell coa, cob;
+EX void copy_metadata(cell *x, const gcell *y) {
+  x->wall = y->wall;
+  x->monst = y->monst;
+  x->item = y->item;
+  x->mondir = y->mondir;
+  x->stuntime = y->stuntime;
+  x->hitpoints = y->hitpoints;
+  x->monmirror = y->monmirror;
+  if(isIcyLand(x)) {
+    x->landparam = y->landparam;
+    }
+  x->wparam = y->wparam;
+  }
+
+#if HDR
+
+extern void playSound(cell *c, const string& fname, int vol);
+
+struct changes_t {
+  vector<reaction_t> rollbacks;
+  vector<reaction_t> commits;
+  bool on;
   
-  bool done;
-  
-  chaos_data() {
-    done = false;
-    ca = (cwt+1).cpeek();
-    cb = (cwt-1).cpeek();
-    if(!items[itOrbChaos] || chaos_forbidden(ca) || chaos_forbidden(cb)) {
-      ca = cb = nullptr;
-      return;
+  void init() {
+    on = true; 
+    for(cell *dc: dcal) ccell(dc);
+    value_keep(kills);
+    value_keep(items);
+    }
+
+  void commit() { 
+    on = false; 
+    for(auto& p: commits) p();
+    rollbacks.clear();
+    commits.clear();
+    }
+
+  void rollback(int pos = 0) { 
+    on = false;
+    while(!rollbacks.empty()) {
+      rollbacks.back()();
+      rollbacks.pop_back();
       }
-    markOrb(itOrbChaos);
-    coa = *ca;
-    cob = *cb;
-    copy_metadata(ca, &cob);
-    copy_metadata(cb, &coa);
-    int sa = ca->mondir - ((cwt+1)+wstep).spin;
-    int sb = cb->mondir - ((cwt-1)+wstep).spin;
-    ca->stuntime = min(ca->stuntime + 3, 15);
-    cb->stuntime = min(cb->stuntime + 3, 15);
-    ca->monmirror = !ca->monmirror;
-    cb->monmirror = !cb->monmirror;
-    if(ca->mondir < ca->type)
-      ca->mondir = ((cwt+1)+wstep-sb).spin;
-    if(cb->mondir < cb->type)
-      cb->mondir = ((cwt+1)+wstep-sa).spin;
+    rollbacks.clear();
+    commits.clear();
     }
   
-  void rollback() {
-    done = true;
-    if(!ca) return;
-    copy_metadata(ca, &coa);
-    copy_metadata(cb, &cob);
+  void ccell(cell *c) {
+    if(!on) return;
+    gcell a = *c;
+    rollbacks.push_back([c, a] { copy_metadata(c, &a); });
     }
   
-  ~chaos_data() {
-    if(!done) {
-      println(hlog, "chaos_data not done");
-      breakhere();
+  template<class T> void value_set(T& what, T value) {
+    if(what == value || !on) return;
+    T old = what;
+    rollbacks.push_back([&what, old] { what = old; });
+    what = value;
+    }
+
+  template<class T> void value_add(T& what, T step) {
+    value_keep(what); what += step;
+    }
+
+  template<class T> void value_inc(T& what) { value_add(what, 1); }
+
+  template<class T> void value_keep(T& what) {
+    if(!on) return;
+    T old = what;
+    rollbacks.push_back([&what, old] { what = old; });
+    }
+
+  template<class T, class U, class V> void map_value(map<T, U>& vmap, V& key) {
+    if(vmap.count(key)) {
+      auto val = vmap[key];
+      at_rollback([&vmap, key, val] { vmap[key] = val; });
+      }
+    else {
+      at_rollback([&vmap, key] { vmap.erase(key); });
       }
     }
   
-  void commit() {
-    if(cb && cb->monst == moPair) {
-      gcell tmp = *ca;
-      ca->monst = moPair;
-      ca->mondir = coa.mondir;
-      killMonster(ca, moPlayer);
-      cb->monst = ca->monst;
-      copy_metadata(ca, &tmp);
-      }
-    if(ca && ca->monst == moPair) {
-      gcell tmp = *cb;
-      cb->monst = moPair;
-      cb->mondir = cob.mondir;
-      killMonster(cb, moPlayer);
-      ca->monst = cb->monst;
-      copy_metadata(cb, &tmp);
-      }
-    done = true;
+  void at_commit(reaction_t act) {
+    if(!on) act();
+    else commits.emplace_back(act);
+    }
+
+  void at_rollback(reaction_t act) {
+    if(on) rollbacks.emplace_back(act);
     }
   };
+#endif
 
+EX changes_t changes;
+
+void apply_chaos() {
+  cell *ca = (cwt+1).cpeek();
+  cell *cb = (cwt-1).cpeek();
+  if(!items[itOrbChaos] || chaos_forbidden(ca) || chaos_forbidden(cb)) return;
+  changes.ccell(ca);
+  changes.ccell(cb);
+  gcell coa = *ca;
+  gcell cob = *cb;
+  copy_metadata(ca, &cob);
+  copy_metadata(cb, &coa);
+  int sa = ca->mondir - ((cwt+1)+wstep).spin;
+  int sb = cb->mondir - ((cwt-1)+wstep).spin;
+  ca->stuntime = min(ca->stuntime + 3, 15);
+  cb->stuntime = min(cb->stuntime + 3, 15);
+  ca->monmirror = !ca->monmirror;
+  cb->monmirror = !cb->monmirror;
+  if(ca->mondir < ca->type)
+    ca->mondir = ((cwt+1)+wstep-sb).spin;
+  if(cb->mondir < cb->type)
+    cb->mondir = ((cwt+1)+wstep-sa).spin;
+  if(cb && cb->monst == moPair) {
+    killMonster(cb, moPlayer);
+    }
+  if(ca && ca->monst == moPair) {
+    killMonster(ca, moPlayer);
+    }
+  }
+  
 bool pcmove::actual_move() {
 
   origd = d;
@@ -423,7 +494,7 @@ bool pcmove::actual_move() {
     }
 
   if(againstRose(cwt.at, c2) && !scentResistant()) {
-    if(!checkonly) addMessage("Those roses smell too nicely. You have to come towards them.");
+    addMessage("Those roses smell too nicely. You have to come towards them.");
     return false;
     }
   
@@ -463,26 +534,18 @@ bool pcmove::actual_move() {
   if(isPushable(c2->wall) && !c2->monst && !nonAdjacentPlayer(c2, cwt.at) && fmsMove) {
     mip = determinePush(cwt, subdir, [c2] (cell *c) { return canPushThumperOn(c, c2, cwt.at); });
     if(mip.d == NO_SPACE) {
-      if(!checkonly) addMessage(XLAT("No room to push %the1.", c2->wall));
+      addMessage(XLAT("No room to push %the1.", c2->wall));
       return false;
       }
-    chaos_data cdata;
-    if(monstersnear(c2, NULL, moPlayer, NULL, cwt.at)) {
-      cdata.rollback();
-      if(!checkonly && errormsgs) wouldkill("%The1 would kill you there!");
-      return false;
-      }
-    if(checkonly) { nextmovetype = lmMove; cdata.rollback(); return true; }
+    nextmovetype = lmMove;
     addMessage(XLAT("You push %the1.", c2->wall));
     lastmovetype = lmPush; lastmove = cwt.at;
     pushThumper(mip);
-    cdata.commit();
     return perform_actual_move();
     }
 
   if(c2->item == itHolyGrail && roundTableRadius(c2) < newRoundTableRadius()) {
-    if(!checkonly)
-      addMessage(XLAT("That was not a challenge. Find a larger castle!"));
+    addMessage(XLAT("That was not a challenge. Find a larger castle!"));
     return false;
     }
 
@@ -496,20 +559,14 @@ bool pcmove::actual_move() {
   if(!c2->monst && cwt.at->wall == waBoat && cwt.at->item != itOrbYendor && boatGoesThrough(c2) && markOrb(itOrbWater) && !nonAdjacentPlayer(c2, cwt.at) && fmsMove) {
 
     if(havePushConflict(cwt.at, checkonly)) return false;
-    chaos_data cdata;
-    if(monstersnear(c2,NULL,moPlayer,NULL,cwt.at)) {
-      if(!checkonly && errormsgs) wouldkill("%The1 would kill you there!");
-      cdata.rollback();
-      return false;
-      }
-    
-    if(checkonly) { nextmovetype = lmMove; cdata.rollback(); return true; }
+
+    if(checkonly) { nextmovetype = lmMove; return true; }
     if(c2->item && !cwt.at->item) moveItem(c2, cwt.at, false), boatmove = true;
     placeWater(c2, cwt.at);
     moveBoat(mi);
+    changes.ccell(c2);
     c2->mondir = revhint(cwt.at, d);
     if(c2->item) boatmove = !boatmove;
-    cdata.commit();
     return perform_actual_move();
     }
   
@@ -522,39 +579,27 @@ bool pcmove::boat_move() {
   if(havePushConflict(cwt.at, checkonly)) return false;
 
   if(againstWind(c2, cwt.at)) {
-    if(!checkonly) 
-      addMessage(XLAT(airdist(c2) < 3 ? "The Air Elemental blows you away!" : "You cannot go against the wind!"));
+    addMessage(XLAT(airdist(c2) < 3 ? "The Air Elemental blows you away!" : "You cannot go against the wind!"));
     return false;
     }
 
   if(againstCurrent(c2, cwt.at) && !markOrb(itOrbWater)) {
     if(markOrb(itOrbFish) || markOrb(itOrbAether) || gravity_state)
       return after_escape();
-    if(!checkonly)
-      addMessage(XLAT("You cannot go against the current!"));
+    addMessage(XLAT("You cannot go against the current!"));
     return false;
     }
 
   if(cwt.at->item == itOrbYendor) {        
     if(markOrb(itOrbFish) || markOrb(itOrbAether) || gravity_state) 
       return after_escape();
-    if(!checkonly)
-      addMessage(XLAT("The Orb of Yendor is locked in with powerful magic."));
+    addMessage(XLAT("The Orb of Yendor is locked in with powerful magic."));
     return false;
     }
 
-  chaos_data cdata;
-  if(monstersnear(c2, NULL, moPlayer, NULL, cwt.at)) {
-    if(!checkonly && errormsgs) 
-      wouldkill("%The1 would kill you there!");
-    cdata.rollback();
-    return false;
-    }
-  
-  if(checkonly) { nextmovetype = lmMove; cdata.rollback(); return true; }
+  nextmovetype = lmMove;
   moveBoat(mi);
   boatmove = true;
-  cdata.commit();
   return perform_actual_move();
   }
 
@@ -603,36 +648,25 @@ bool pcmove::after_escape() {
 
   if(c2->wall == waBigStatue && !c2->monst && !nonAdjacentPlayer(c2, cwt.at) && fmsMove) {
     if(!canPushStatueOn(cwt.at)) {
-      if(!checkonly) {
-        if(isFire(cwt.at))
-          addMessage(XLAT("You have to escape first!"));
-        else
-          addMessage(XLAT("There is not enough space!"));
-        }
+      if(isFire(cwt.at))
+        addMessage(XLAT("You have to escape first!"));
+      else
+        addMessage(XLAT("There is not enough space!"));
       return false;
       }
     
     if(havePushConflict(cwt.at, checkonly)) return false;
     
-    eWall save_c2 = c2->wall;
-    eWall save_cw = cwt.at->wall;
+    changes.ccell(c2);
+    changes.ccell(cwt.at);
+    
     c2->wall = cwt.at->wall;
     if(doesnotFall(cwt.at))
       cwt.at->wall = waBigStatue;
       
-    chaos_data cdata;
-    
-    if(monstersnear(c2,NULL,moPlayer,NULL,cwt.at)) {
-      cdata.rollback();
-      if(!checkonly && errormsgs) wouldkill("%The1 would kill you there!");
-      c2->wall = save_c2; cwt.at->wall = save_cw;
-      return false;
-      }        
-        
-    if(checkonly) { cdata.rollback(); c2->wall = save_c2; cwt.at->wall = save_cw; nextmovetype = lmMove; return true; }
+    nextmovetype = lmMove;
     addMessage(XLAT("You push %the1 behind you!", waBigStatue));
     animateMovement(mi.rev(), LAYER_BOAT);
-    cdata.commit();
     return perform_actual_move();
     }
 
@@ -650,15 +684,12 @@ bool pcmove::after_escape() {
     
   if(attackable && fmsAttack) {
     if(checkNeedMove(checkonly, true)) return false;
-    if(monstersnear(cwt.at,c2,moPlayer,NULL,cwt.at)) {
-      if(!checkonly && errormsgs) wouldkill("%The1 would get you!");
-      return false;
-      }
-    if(checkonly) { nextmovetype = nm ? lmAttack : lmSkip; return true; }
+    nextmovetype = nm ? lmAttack : lmSkip;
     if(c2->wall == waSmallTree) {
       drawParticles(c2, winf[c2->wall].color, 4);
       addMessage(XLAT("You chop down the tree."));
       playSound(c2, "hit-axe" + pick123());
+      changes.ccell(c2);
       c2->wall = waNone;
       return swing();
       }
@@ -666,6 +697,7 @@ bool pcmove::after_escape() {
       drawParticles(c2, winf[c2->wall].color, 8);
       addMessage(XLAT("You start chopping down the tree."));
       playSound(c2, "hit-axe" + pick123());
+      changes.ccell(c2);
       c2->wall = waSmallTree;
       return swing();
       }
@@ -681,14 +713,14 @@ bool pcmove::after_escape() {
     return false;
     }
   else if(c2->monst == moKnight) {
-    if(!checkonly) camelot::knightFlavorMessage(c2);
+    camelot::knightFlavorMessage(c2);
     return false;
     }
   else if(c2->monst && (!isFriendly(c2) || c2->monst == moTameBomberbird || isMountable(c2->monst))
     && !(peace::on && !isMultitile(c2->monst) && !good_tortoise)) 
     return attack();
   else if(!passable(c2, cwt.at, P_USEBOAT | P_ISPLAYER | P_MIRROR | P_MONSTER)) {
-    if(!checkonly) tell_why_impassable();
+    tell_why_impassable();
     return false;
     }
   else if(fmsMove) 
@@ -709,64 +741,12 @@ bool pcmove::move_if_okay() {
       return false;
     }
 
-  chaos_data cdata;
-  if(monstersnear(c2, NULL, moPlayer, NULL, cwt.at)) {
-    cdata.rollback();
-    if(checkonly) return false;
-
-    if(items[itOrbFlash]) {
-      if(checkonly) { nextmovetype = lmInstant; return true; }
-      if(orbProtection(itOrbFlash)) return true;
-      activateFlash();
-      checkmove();
-      return true;
-      }
-
-    if(items[itOrbLightning]) {
-      if(checkonly) { nextmovetype = lmInstant; return true; }
-      if(orbProtection(itOrbLightning)) return true;
-      activateLightning();
-      checkmove();
-      return true;
-      }
-
-    if(who_kills_me == moOutlaw && items[itRevolver]) {
-      for(int i=0; i<c2->type; i++) {
-        cell *c3 = c2->move(i);
-        if(c3) for(int i=0; i<c3->type; i++) {
-          cell *c4 = c3->move(i);
-          if(c4 && c4->monst == moOutlaw) {
-            eItem i = targetRangedOrb(c4, roCheck);
-            if(i == itRevolver) { 
-              targetRangedOrb(c4, roKeyboard);
-              return false;
-              }
-            }
-          }
-        }
-      }
-
-    if(!checkonly && errormsgs) 
-      wouldkill("%The1 would kill you there!");
+  if(switchplace_prevent(cwt.at, c2, checkonly))
     return false;
-    }
-
-  if(switchplace_prevent(cwt.at, c2, checkonly)) {
-    cdata.rollback();  
+  if(!checkonly && warningprotection_hit(do_we_stab_a_friend(cwt.at, c2, moPlayer)))
     return false;
-    }
-  if(!checkonly && warningprotection_hit(do_we_stab_a_friend(cwt.at, c2, moPlayer))) {
-    cdata.rollback();
-    return false;
-    }
   
-  if(checkonly) { 
-    cdata.rollback();
-    nextmovetype = lmMove; 
-    return true;
-    }
-  
-  cdata.commit();
+  nextmovetype = lmMove; 
   return perform_actual_move();
   }
 
@@ -810,15 +790,16 @@ bool pcmove::attack() {
   
   if(!ca) {
     if(forcedmovetype == fmAttack) {
-      if(monstersnear(cwt.at,c2,moPlayer,NULL,cwt.at)) {
-        if(!checkonly && errormsgs) wouldkill("%The1 would get you!");
+      if(monstersnear(cwt.at,moPlayer,NULL,cwt.at)) {
+        changes.rollback();
+        if(errormsgs && !checkonly) wouldkill("%The1 would get you!");
         return false;
         }
-      if(checkonly) { nextmovetype = lmSkip; return true; }
+      nextmovetype = lmSkip;
       addMessage(XLAT("You swing your sword at %the1.", c2->monst));
       return swing();
       }
-    if(!checkonly) tell_why_cannot_attack();
+    tell_why_cannot_attack();
     return false;
     }
     
@@ -842,29 +823,25 @@ bool pcmove::attack() {
   if(!(isWatery(cwt.at) && c2->monst == moWaterElemental) && checkNeedMove(checkonly, true))
     return false;
   
-  if(monstersnear(cwt.at, c2, moPlayer, mip.t, cwt.at)) {
-    if(errormsgs && !checkonly)
-      wouldkill("You would be killed by %the1!");          
-    return false;
-    }
-
   if(c2->monst == moTameBomberbird && warningprotection_hit(moTameBomberbird)) return false;
   
-  if(checkonly) { nextmovetype = lmAttack; return true; }
+  nextmovetype = lmAttack;
 
   mirror::act(origd, mirror::SPINMULTI | mirror::ATTACK);
   
   int tk = tkills();
 
   if(good_tortoise) {
-    items[itBabyTortoise] += 4;
-    updateHi(itBabyTortoise, items[itBabyTortoise]);
-    c2->item = itBabyTortoise;
-    tortoise::babymap[c2] = tortoise::seekbits;
-    playSound(c2, playergender() ? "heal-princess" : "heal-prince");
-    addMessage(XLAT(playergender() == GEN_F ? "You are now a tortoise heroine!" : "You are now a tortoise hero!"));
-    c2->stuntime = 2;
-    achievement_collection(itBabyTortoise);
+    changes.at_commit([c2] {
+      items[itBabyTortoise] += 4;
+      updateHi(itBabyTortoise, items[itBabyTortoise]);
+      c2->item = itBabyTortoise;
+      tortoise::babymap[c2] = tortoise::seekbits;
+      playSound(c2, playergender() ? "heal-princess" : "heal-prince");
+      addMessage(XLAT(playergender() == GEN_F ? "You are now a tortoise heroine!" : "You are now a tortoise hero!"));
+      c2->stuntime = 2;
+      achievement_collection(itBabyTortoise);
+      });
     }
   else {
     eMonster m = c2->monst;
@@ -873,13 +850,15 @@ bool pcmove::attack() {
         markOrb(itOrbSlaying);
       if(c2->monst == moTerraWarrior && hrand(100) > 2 * items[itTerra]) {
         if(hrand(2 + jiangshi_on_screen) < 2)
-          wandering_jiangshi++;
+          changes.value_add(wandering_jiangshi, 1);
         }
       attackMonster(c2, attackflags | AF_MSG, moPlayer);
       if(m == moRusalka) {
+        changes.ccell(cwt.at);
         if(cwt.at->wall == waNone) cwt.at->wall = waShallow;
         else if(cwt.at->wall == waShallow) cwt.at->wall = waDeepWater;
         }
+      changes.ccell(c2);
       // salamanders are stunned for longer time when pushed into a wall
       if(c2->monst == moSalamander && (mip.t == c2 || !mip.t)) c2->stuntime = 10;
       if(!c2->monst) produceGhost(c2, m, moPlayer);
@@ -891,6 +870,16 @@ bool pcmove::attack() {
   sideAttack(cwt.at, d, moPlayer, tkills() - tk);
   lastmovetype = lmAttack; lastmove = c2;
   swordAttackStatic();
+
+  if(monstersnear(cwt.at, moPlayer, nullptr, cwt.at)) {
+    changes.rollback();
+    if(errormsgs && !checkonly)
+      wouldkill("You would be killed by %the1!");
+    return false;
+    }
+  if(checkonly) return true;
+  if(changes.on) changes.commit();
+
   return after_move();
   }
 
@@ -898,20 +887,6 @@ EX bool chaos_forbidden(cell *c) {
   return among(c->wall, waMirrorWall, waBarrier, waRoundTable) || isMultitile(c->monst);
   }
 
-EX void copy_metadata(cell *x, gcell *y) {
-  x->wall = y->wall;
-  x->monst = y->monst;
-  x->item = y->item;
-  x->mondir = y->mondir;
-  x->stuntime = y->stuntime;
-  x->hitpoints = y->hitpoints;
-  x->monmirror = y->monmirror;
-  if(isIcyLand(x)) {
-    x->landparam = y->landparam;
-    }
-  x->wparam = y->wparam;
-  }
-
 bool pcmove::perform_actual_move() {
   cell*& c2 = mi.t;
   flipplayer = true; if(multi::players > 1) multi::flipped[multi::cpid] = true;
@@ -989,10 +964,63 @@ void pcmove::handle_friendly_ivy() {
 
 bool pcmove::perform_move_or_jump() {
   lastmovetype = lmMove; lastmove = cwt.at;
+  apply_chaos();
 
   stabbingAttack(cwt.at, mi.t, moPlayer);
   cell *c1 = cwt.at;
+  changes.value_keep(cwt);
   cwt += wstep;
+  
+  mirror::act(origd, mirror::SPINMULTI | mirror::ATTACK | mirror::GO);
+
+  playerMoveEffects(c1, mi.t);
+
+  if(mi.t->monst == moFriendlyIvy) changes.ccell(mi.t), mi.t->monst = moNone;
+  
+  if(monstersnear(cwt.at, moPlayer, nullptr, c1)) {
+    changes.rollback();
+
+    /* todo
+    if(items[itOrbFlash]) {
+      if(checkonly) { nextmovetype = lmInstant; return true; }
+      if(orbProtection(itOrbFlash)) return true;
+      activateFlash();
+      checkmove();
+      return true;
+      }
+
+    if(items[itOrbLightning]) {
+      if(checkonly) { nextmovetype = lmInstant; return true; }
+      if(orbProtection(itOrbLightning)) return true;
+      activateLightning();
+      checkmove();
+      return true;
+      }
+
+    if(who_kills_me == moOutlaw && items[itRevolver]) {
+      for(int i=0; i<c2->type; i++) {
+        cell *c3 = c2->move(i);
+        if(c3) for(int i=0; i<c3->type; i++) {
+          cell *c4 = c3->move(i);
+          if(c4 && c4->monst == moOutlaw) {
+            eItem i = targetRangedOrb(c4, roCheck);
+            if(i == itRevolver) { 
+              targetRangedOrb(c4, roKeyboard);
+              return false;
+              }
+            }
+          }
+        }
+      }
+    */
+
+    if(errormsgs && !checkonly) wouldkill("%The1 would kill you there!");
+    return false;
+    }
+  
+  if(checkonly) return true;
+  if(changes.on) changes.commit();
+
   if(switchplaces) {
     indAnimateMovement(mi, LAYER_SMALL);
     indAnimateMovement(mi.rev(), LAYER_SMALL);
@@ -1001,12 +1029,6 @@ bool pcmove::perform_move_or_jump() {
   else
     animateMovement(mi, LAYER_SMALL);
   current_display->which_copy = current_display->which_copy * adj(mi);
-  
-  mirror::act(origd, mirror::SPINMULTI | mirror::ATTACK | mirror::GO);
-
-  playerMoveEffects(c1, mi.t);
-
-  if(mi.t->monst == moFriendlyIvy) mi.t->monst = moNone;
 
   countLocalTreasure();
   landvisited[cwt.at->land] = true;
@@ -1023,13 +1045,16 @@ bool pcmove::stay() {
   lastmovetype = lmSkip; lastmove = NULL;
   if(checkNeedMove(checkonly, false))
     return false;
-  if(monstersnear(cwt.at, NULL, moPlayer, NULL, cwt.at)) {
+  swordAttackStatic();
+  nextmovetype = lmSkip;
+  if(monstersnear(cwt.at, moPlayer, nullptr, cwt.at)) {
+    changes.rollback();
     if(errormsgs && !checkonly) 
       wouldkill("%The1 would get you!");
     return false;
     }
-  if(checkonly) { nextmovetype = lmSkip; return true; }
-  swordAttackStatic();
+  if(checkonly) return true;
+  if(changes.on) changes.commit();
   if(d == -2) 
     dropGreenStone(cwt.at);
   if(cellUnstable(cwt.at) && !markOrb(itOrbAether))
@@ -1138,7 +1163,8 @@ EX bool playerInPower() {
 EX void playerMoveEffects(cell *c1, cell *c2) {
 
   if(peace::on) items[itOrbSword] = c2->land == laBurial ? 100 : 0;
-
+  
+  changes.value_keep(sword::dir[multi::cpid]);
   sword::dir[multi::cpid] = sword::shift(c1, c2, sword::dir[multi::cpid]);
   
   destroyWeakBranch(c1, c2, moPlayer);
@@ -1172,7 +1198,7 @@ EX void playerMoveEffects(cell *c1, cell *c2) {
     c2->landparam = 40;
   
   if((c2->land == laHauntedWall || c2->land == laHaunted) && !hauntedWarning) {
-    hauntedWarning = true;
+    changes.value_set(hauntedWarning, true);
     addMessage(XLAT("You become a bit nervous..."));
     addMessage(XLAT("Better not to let your greed make you stray from your path."));
     playSound(c2, "nervous");
@@ -1344,14 +1370,12 @@ EX bool havePushConflict(cell *pushto, bool checkonly) {
   if(pushto && multi::activePlayers() > 1) {
     for(int i=0; i<multi::players; i++)  if(i != multi::cpid && multi::playerActive(i))
       if(multi::origpos[i] == pushto || multi::origtarget[i] == pushto) {
-        if(!checkonly) 
-          addMessage(XLAT("Cannot push into another player!"));
+        addMessage(XLAT("Cannot push into another player!"));
         return true;
         }
     for(int i=0; i<isize(stalemate::moves); i++)  {
       if(pushto == stalemate::moves[i].pushto) {
-        if(!checkonly)
-          addMessage(XLAT("Cannot push into the same location!"));
+        addMessage(XLAT("Cannot push into the same location!"));
         return true;
         }
       }
diff --git a/sound.cpp b/sound.cpp
index c0139c52..fae4b056 100644
--- a/sound.cpp
+++ b/sound.cpp
@@ -216,6 +216,7 @@ string wheresounds = HYPERPATH "sounds/";
 hookset<bool(const string& s, int vol)> *hooks_sound;
 
 EX void playSound(cell *c, const string& fname, int vol IS(100)) {
+  LATE( hr::playSound(c, fname, vol); )
   if(effvolume == 0) return;
   if(callhandlers(false, hooks_sound, fname, vol)) return;
   // printf("Play sound: %s\n", fname.c_str());
diff --git a/system.cpp b/system.cpp
index 5d94e29a..e978fc62 100644
--- a/system.cpp
+++ b/system.cpp
@@ -1518,7 +1518,6 @@ EX void finishAll() {
 #if CAP_SAVE
   saveStats();
 #endif
-  offscreen.clear();
   clearMemory();
 #if ISMOBILE==0
   cleargraph();
diff --git a/yendor.cpp b/yendor.cpp
index 3a8695d8..9f37d4c6 100644
--- a/yendor.cpp
+++ b/yendor.cpp
@@ -750,6 +750,7 @@ EX namespace yendor {
     }
     
   EX void collected(cell* c2) {
+    LATE( collected(c2); )
     playSound(c2, "tada");
     items[itOrbShield] += 31;
     for(int i=0; i<isize(yendor::yi); i++)