diff --git a/classes.cpp b/classes.cpp
index 46386dc7..ebdd0c48 100644
--- a/classes.cpp
+++ b/classes.cpp
@@ -1241,7 +1241,7 @@ enum eItem { itNone, itDiamond, itGold, itSpice, itRuby, itElixir, itShard, itBo
 
 // --- wall types ---
 
-const int walltypes = 103;
+const int walltypes = 104;
 
 struct walltype {
   char  glyph;
@@ -1427,6 +1427,7 @@ walltype winf[walltypes] = {
   { 'S', 0xB0B0B0, "warrior statue", NODESCYET},
   { '=', 0xB0B0B0, "bubbling slime", NODESCYET},
   { '^', 0xD00000, "arrow trap", NODESCYET},
+  { '=', 0xE2E2E2, "mercury river", NODESCYET},
   };
 
 enum eWall { waNone, waIcewall, waBarrier, waFloorA, waFloorB, waCavewall, waCavefloor, waDeadTroll, waDune,
@@ -1460,12 +1461,12 @@ enum eWall { waNone, waIcewall, waBarrier, waFloorA, waFloorB, waCavewall, waCav
   waPetrifiedBridge,
   waTempBridgeBlocked,
   waTerraWarrior, waBubble,
-  waArrowTrap
+  waArrowTrap, waMercury
   };
 
 // --- land types ---
 
-const int landtypes = 76;
+const int landtypes = 77;
 
 struct landtype {
   int color;
@@ -1651,6 +1652,7 @@ const landtype linf[landtypes] = {
   { 0xA06000, "Alchemy II", NODESCYET},
   { 0x8080FF, "Blizzard", NODESCYET},
   { 0x207068, "Hunting Ground", NODESCYET},
+  { 0xE2725B, "Terracotta Army", NODESCYET},
   { 0xE2725B, "Terracotta Army", NODESCYET}
   };
 
@@ -1671,7 +1673,7 @@ enum eLand { laNone, laBarrier, laCrossroads, laDesert, laIce, laCaves, laJungle
   laPrairie, laBull, laCrossroads5, laCA,
   laMirrorWall, laMirrored, laMirrorWall2, laMirrored2,
   laMirrorOld,
-  laAlchemy2, laBlizzard, laDogPlains, laTerracotta
+  laAlchemy2, laBlizzard, laDogPlains, laTerracotta, laMercuryRiver
   };
 
 // cell information for the game
diff --git a/flags.cpp b/flags.cpp
index 3380f235..2a7b3ede 100644
--- a/flags.cpp
+++ b/flags.cpp
@@ -24,7 +24,8 @@ bool isWatery(cell *c) {
   }
 
 bool isChasmy(cell *c) {
-  return c->wall == waChasm || c->wall == waSulphur || c->wall == waSulphurC || c->wall == waBubble;
+  return c->wall == waChasm || c->wall == waSulphur || c->wall == waSulphurC || c->wall == waBubble ||
+    c->wall == waMercury;
   }
 
 bool isWateryOrBoat(cell *c) {
@@ -588,6 +589,13 @@ bool survivesWater(eMonster m) {
     m == moTortoise; // Tortoises and Ivies survive, but don't go through water
   }
 
+// survives Mercury or Sulphur
+bool survivesPoison(eMonster m, eWall p) {
+  return
+    isGhost(m) || m == moWitchGhost || m == moShadow ||
+    isBird(m) || m == moAirElemental || isDragon(m);
+  }
+
 // flying even if stunned
 bool isPermanentFlying(eMonster m) {
   return m == moAirElemental || isGhost(m);
diff --git a/game.cpp b/game.cpp
index d6828186..10c2d441 100644
--- a/game.cpp
+++ b/game.cpp
@@ -5123,10 +5123,16 @@ void moverefresh(bool turn = true) {
         playSound(c, "click");
         }
       else if(isChasmy(c) || isWatery(c)) {
-        c->wall = waReptileBridge;
+        if(c->wall == waMercury) {
+          fallMonster(c, AF_FALL);
+          c->wall = waNone;
+          }
+        else {
+          c->wall = waReptileBridge;
+          c->wparam = reptilemax();
+          c->monst = moNone;
+          }
         c->item = itNone;
-        c->wparam = reptilemax();
-        c->monst = moNone;
         playSound(c, "click");
         }
       }
@@ -5199,6 +5205,20 @@ void moverefresh(bool turn = true) {
         fallMonster(c, AF_FALL);
         }
       }
+    else if(c->wall == waSulphur || c->wall == waSulphurC || c->wall == waMercury) {
+      if(c->monst && !survivesPoison(c->monst, c->wall)) {
+        playSound(c, "splash"+pick12());
+        if(isNonliving(c->monst))
+          addMessage(XLAT("%The1 sinks!", c->monst));
+        else 
+          addMessage(XLAT("%The1 drowns!", c->monst));
+        if(isBull(c->monst)) {
+          addMessage(XLAT("%The1 is filled!", c->wall));
+          c->wall = waNone;
+          }
+        fallMonster(c, AF_FALL);
+        }
+      }
     else if(!isWateryOrBoat(c)) {
       if(c->monst == moGreaterShark)
         c->monst = moGreaterM;
diff --git a/graph.cpp b/graph.cpp
index 8eefb314..d358aa28 100644
--- a/graph.cpp
+++ b/graph.cpp
@@ -2353,7 +2353,7 @@ void setcolors(cell *c, int& wcol, int &fcol) {
     case laBurial: case laTrollheim: case laBarrier: case laOceanWall:
     case laCrossroads2: case laCrossroads3: case laCrossroads4: case laCrossroads5:
     case laRose: case laPower: case laWildWest: case laHalloween: case laRedRock:
-    case laDragon: case laStorms: case laTerracotta:
+    case laDragon: case laStorms: case laTerracotta: case laMercuryRiver:
       fcol = linf[c->land].color; break;
 
     case laDesert: fcol = 0xEDC9AF; break;
@@ -2616,7 +2616,7 @@ void setcolors(cell *c, int& wcol, int &fcol) {
      fcol = wcol = winf[c->wall].color; */
 
   // floors become fcol
-  if(c->wall == waSulphur || c->wall == waSulphurC || c->wall == waPlatform)
+  if(c->wall == waSulphur || c->wall == waSulphurC || c->wall == waPlatform || c->wall == waMercury)
     fcol = wcol;
   
   if(isAlch(c)) {
@@ -2824,8 +2824,8 @@ void placeSidewall(cell *c, int i, int sidepar, const transmatrix& V, bool warp,
   if(shmup::on || purehepta) warp = false;
   if(warp && !ishept(c) && (!c->mov[i] || !ishept(c->mov[i]))) return;
   int prio;
-  if(mirr) prio = PPR_GLASS - 2;
-  else if(sidepar == SIDE_WALL) prio = PPR_WALL3 - 2;
+  /* if(mirr) prio = PPR_GLASS - 2;
+  else */ if(sidepar == SIDE_WALL) prio = PPR_WALL3 - 2;
   else if(sidepar == SIDE_WTS3) prio = PPR_WALL3 - 2;
   else if(sidepar == SIDE_LAKE) prio = PPR_LAKEWALL;
   else if(sidepar == SIDE_LTOB) prio = PPR_INLAKEWALL;
@@ -2834,8 +2834,10 @@ void placeSidewall(cell *c, int i, int sidepar, const transmatrix& V, bool warp,
   
   transmatrix V2 = V * ddspin(c, i);
   
-  int aw = away(V2); prio += aw;
+  /* int aw = away(V2); prio += aw;
   if(!detaillevel && aw < 0) return;
+  */
+  
   // queuepoly(V2 * xpush(.1), shSnowball, aw ? 0xFFFFFFFF : 0xFF0000FF);
   // prio += c->cpdist - c->mov[i]->cpdist;  
 
@@ -3255,6 +3257,7 @@ void drawcell(cell *c, transmatrix V, int spinv, bool mirrored) {
       c->land == laReptile ? 0 :
       c->land == laDogPlains ? 1 :
       c->land == laTerracotta ? 1 :
+      c->land == laMercuryRiver ? 0 :
       2;
     
     if(c->land == laAlchemy2) {
@@ -3870,7 +3873,7 @@ void drawcell(cell *c, transmatrix V, int spinv, bool mirrored) {
         int col = winf[waGlass].color;
         int dcol = darkena(col, 0, 0x80);
         transmatrix Vdepth = mscale((*Vdp), geom3::WALL);
-        queuepolyat(Vdepth, shMFloor[ct6], dcol, PPR_GLASS);
+        queuepolyat(Vdepth, shMFloor[ct6], dcol, PPR_WALL); // GLASS
         if(validsidepar[SIDE_WALL]) forCellIdEx(c2, i, c) 
           placeSidewall(c, i, SIDE_WALL, (*Vdp), false, true, dcol);
         }
@@ -3982,7 +3985,7 @@ void drawcell(cell *c, transmatrix V, int spinv, bool mirrored) {
           int col = winf[c->wall].color;
           int dcol = darkena(col, 0, 0xC0);
           transmatrix Vdepth = mscale((*Vdp), geom3::WALL);
-          queuepolyat(Vdepth, shMFloor[ct6], dcol, PPR_GLASS);
+          queuepolyat(Vdepth, shMFloor[ct6], dcol, PPR_WALL); // GLASS
           if(validsidepar[SIDE_WALL]) forCellIdEx(c2, i, c) 
             placeSidewall(c, i, SIDE_WALL, (*Vdp), false, true, dcol);
           }
@@ -4011,7 +4014,7 @@ void drawcell(cell *c, transmatrix V, int spinv, bool mirrored) {
         queuepoly(V, shBigCarpet3, darkena(0xC09F00, 0, 0xFF));
         }
 
-      else if(xch != '.' && xch != '+' && xch != '>' && xch != ':'&& xch != '-' && xch != ';' && c->wall != waSulphur && xch != ',')
+      else if(xch != '.' && xch != '+' && xch != '>' && xch != ':'&& xch != '-' && xch != ';' && c->wall != waSulphur && c->wall != waMercury && xch != ',')
         error = true;
       }
 
@@ -4311,7 +4314,7 @@ void drawcell(cell *c, transmatrix V, int spinv, bool mirrored) {
 #endif
     }
     
-    if(c->bardir != NODIR && c->bardir != NOBARRIERS && c->land != laHauntedWall &&
+    if(vid.grid && c->bardir != NODIR && c->bardir != NOBARRIERS && c->land != laHauntedWall &&
       c->barleft != NOWALLSEP_USED) {
       int col = darkena(0x505050, 0, 0xFF);
       queueline(tC0(V), V*tC0(heptmove[c->bardir]), col, 2);
diff --git a/landgen.cpp b/landgen.cpp
index b6b10385..9c5b98ba 100644
--- a/landgen.cpp
+++ b/landgen.cpp
@@ -223,7 +223,7 @@ int isNative(eLand l, eMonster m) {
     case laAlchemy2:
       return m == moLemur ? 2 : 0;
     
-    case laTerracotta:
+    case laTerracotta: case laMercuryRiver:
       return m == moJiangshi ? 2 : m == moTerraWarrior ? 1 : 0;
     
     case laBlizzard:
@@ -321,7 +321,7 @@ eItem treasureType(eLand l) {
     case laPrairie: return itGreenGrass;
     
     case laAlchemy2: return itAlchemy2;
-    case laTerracotta: return itTerra;
+    case laTerracotta: case laMercuryRiver: return itTerra;
     case laBlizzard: return itBlizzard;
     case laDogPlains: return itDogPlains;
     
@@ -783,7 +783,7 @@ bool landUnlocked(eLand l) {
     case laDogPlains:
       return true;
     
-    case laTerracotta:
+    case laTerracotta: case laMercuryRiver:
       return gold() >= 60;
     
     case laBlizzard:
@@ -988,6 +988,10 @@ void setbarrier(cell *c) {
     c->land = laMirrorWall2;
   else if(c->barleft == laMirrored || c->barright == laMirrored)
     c->land = laMirrorWall;
+  else if(c->barleft == laTerracotta && c->barright == laTerracotta) {
+    c->land = laMercuryRiver;
+    c->wall = waMercury;
+    }
   else {
     c->wall = waBarrier;
     c->land = laBarrier;
@@ -1440,7 +1444,8 @@ void extendCR5(cell *c) {
 bool isbar4(cell *c) {
   return
     c->wall == waBarrier || c->land == laElementalWall || 
-    c->land == laMirrorWall || c->land == laMirrorWall2;
+    c->land == laMirrorWall || c->land == laMirrorWall2 ||
+    c->land == laMercuryRiver;
   }  
 
 void extendBarrier(cell *c) {
@@ -1453,7 +1458,7 @@ void extendBarrier(cell *c) {
   
   // printf("build barrier at %p", c);
   if(c->land == laBarrier || c->land == laElementalWall || c->land == laHauntedWall || c->land == laOceanWall || 
-    c->land == laMirrorWall || c->land == laMirrorWall2) { 
+    c->land == laMirrorWall || c->land == laMirrorWall2 || c->land == laMercuryRiver) { 
     // printf("-> ready\n");
     return;
     }
@@ -1718,7 +1723,8 @@ hookset<eLand(eLand)> *hooks_nextland;
 
 eLand getNewLand(eLand old) {
 
-  if(old == laMirror && !chaosmode && hrand(10) < 8) return laMirrored;
+  if(old == laMirror && !chaosmode && hrand(10) >= (tactic::on ? 0 : markOrb(itOrbLuck) ? 5 : 2)) return laMirrored;
+  if(old == laTerracotta && !chaosmode && hrand(5) >= (tactic::on ? 0 : markOrb(itOrbLuck) ? 2 : 1)) return laTerracotta;
     
   eLand l = callhandlers(laNone, hooks_nextland, old);
   if(l) return l;
@@ -3180,6 +3186,8 @@ void buildBigStuff(cell *c, cell *from) {
     c->land == laCrossroads2 ? 10000 : 
     c->land == laCrossroads5 ? 10000 : 
     c->land == laCrossroads4 ? 0 : 
+    (c->land == laMirror && !yendor::generating) ? 6000 :
+    c->land == laTerracotta ? 250 :
     (tactic::on && !tactic::trailer) ? 0 :
     c->land == laCaribbean ? 500 :
     (c->land == laWarpSea || c->land == laWarpCoast) ? 500 :
@@ -3190,7 +3198,6 @@ void buildBigStuff(cell *c, cell *from) {
     (c->land == laGraveyard && items[itBone] >= 10) ? 120 :
     c->land == laOcean ? (deepOcean ? (purehepta ? 250 : 2000) : 0) :
     c->land == laDragon ? 120 :
-    (c->land == laMirror && !yendor::generating) ? 6000 :
     50))
   {
     
@@ -4046,16 +4053,19 @@ void setdist(cell *c, int d, cell *from) {
           cwstep(cw); cc[3] = cw.c; cwrevstep(cw); cc[4] = cw.c;
           cwrevstep(cw2); cc[1] = cw2.c; cwrevstep(cw2); cc[0] = cw2.c;
           bool ok = true;
-          for(int i=1; i<4; i++) {
-            forCellEx(c2, cc[i]) if(c2->wall == waArrowTrap) ok = false;
+          for(int i=0; i<5; i++) {
             if(cc[i]->land != laNone && cc[i]->land != laTerracotta) ok = false;
             if(cc[i]->bardir != NODIR) ok = false;
-            cc[i]->bardir = NOBARRIERS;
+            }
+          for(int i=1; i<4; i++) {
+            forCellEx(c2, cc[i]) if(c2->wall == waArrowTrap) ok = false;
             }
           if(ok) {
             for(int i=1; i<4; i++) 
               cc[i]->wall = waArrowTrap,
               cc[i]->wparam = 0;
+            for(int i=0; i<5; i++) 
+              cc[i]->bardir = NOBARRIERS;
             cc[0]->wall = waStone;
             cc[4]->wall = waStone;
             }
diff --git a/polygons.cpp b/polygons.cpp
index 0476d4cc..3c8750d6 100644
--- a/polygons.cpp
+++ b/polygons.cpp
@@ -556,7 +556,7 @@ void drawqueue() {
   
 #else
   
-  int qp[PPR_MAX];
+  int qp[PPR_MAX], qp0[PPR_MAX];
   for(int a=0; a<PPR_MAX; a++) qp[a] = 0;
   
   for(int i = 0; i<siz; i++) {
@@ -570,12 +570,19 @@ void drawqueue() {
   int total = 0;
   for(int a=0; a<PPR_MAX; a++) {
     int b = qp[a];
-    qp[a] = total; total += b;
+    qp0[a] = qp[a] = total; total += b;
     }
   
   ptds2.resize(siz);
   
   for(int i = 0; i<siz; i++) ptds2[qp[ptds[i].prio]++] = &ptds[i];
+  
+  for(int p: {PPR_REDWALLs, PPR_REDWALLs2, PPR_REDWALLs3, PPR_WALL3s})
+  sort(&ptds2[qp0[p]], &ptds2[qp[p]], 
+    [] (polytodraw* p1, polytodraw* p2) {
+      return intval(p1->u.poly.V * xpush0(.1), C0)
+        > intval(p2->u.poly.V * xpush0(.1), C0);
+      });
 
 #endif
   profile_stop(3);