diff --git a/polymer/eduke32/build/src/build.c b/polymer/eduke32/build/src/build.c
index 76e0af268..904bcd73b 100644
--- a/polymer/eduke32/build/src/build.c
+++ b/polymer/eduke32/build/src/build.c
@@ -3411,10 +3411,9 @@ void overheadeditor(void)
                     ulz[0] &= ~255;
                     ulz[1] = ulz[0] + swsecheight;
 
-                    if (maxceilz >= ulz[0] || ulz[0] >= ulz[1] || ulz[1] >= minfloorz)
+                    if (maxceilz >= ulz[0] || ulz[1] >= minfloorz)
                     {
                         message("Too little z headroom for sandwiching");
-//                        message("Internal error while sandwiching: z values wrong");
                         goto end_yax;
                     }
                 }
diff --git a/polymer/eduke32/build/src/engine.c b/polymer/eduke32/build/src/engine.c
index a37a55fee..a63b63a29 100644
--- a/polymer/eduke32/build/src/engine.c
+++ b/polymer/eduke32/build/src/engine.c
@@ -9740,6 +9740,9 @@ int32_t setgamemode(char davidoption, int32_t daxdim, int32_t daydim, int32_t da
 {
     int32_t i, j;
 
+    daxdim = max(640, daxdim);
+    daydim = max(480, daydim);
+
 #ifdef USE_OPENGL
     extern char nogl;
 
diff --git a/polymer/eduke32/source/actors.c b/polymer/eduke32/source/actors.c
index 34c892223..e2b409f0d 100644
--- a/polymer/eduke32/source/actors.c
+++ b/polymer/eduke32/source/actors.c
@@ -5696,6 +5696,9 @@ ACTOR_STATIC void G_MoveEffectors(void)   //STATNUM 3
 
             if (s->xvel)
             {
+#ifdef YAX_ENABLE
+                int32_t firstrun = 1;
+#endif
                 x = getangle(sprite[s->owner].x-s->x,sprite[s->owner].y-s->y);
                 q = G_GetAngleDelta(s->ang,x)>>3;
 
@@ -5749,38 +5752,52 @@ ACTOR_STATIC void G_MoveEffectors(void)   //STATNUM 3
                 x = (s->xvel*sintable[s->ang&2047])>>14;
 
                 TRAVERSE_CONNECT(p)
-                if (sector[g_player[p].ps->cursectnum].lotag != 2)
                 {
-                    if (g_playerSpawnPoints[p].os == s->sectnum)
+                    if (g_player[p].ps->cursectnum < 0)
                     {
-                        g_playerSpawnPoints[p].ox += m;
-                        g_playerSpawnPoints[p].oy += x;
+                        // might happen when squished into void space
+//                        initprintf("cursectnum < 0!\n");
+                        break;
                     }
 
-                    if (s->sectnum == sprite[g_player[p].ps->i].sectnum)
+                    if (sector[g_player[p].ps->cursectnum].lotag != 2)
                     {
-                        rotatepoint(s->x,s->y,g_player[p].ps->pos.x,g_player[p].ps->pos.y,q,&g_player[p].ps->pos.x,&g_player[p].ps->pos.y);
-
-                        g_player[p].ps->pos.x += m;
-                        g_player[p].ps->pos.y += x;
-
-                        g_player[p].ps->bobposx += m;
-                        g_player[p].ps->bobposy += x;
-
-                        g_player[p].ps->ang += q;
-
-                        if (g_netServer || numplayers > 1)
+                        if (g_playerSpawnPoints[p].os == s->sectnum)
                         {
-                            g_player[p].ps->opos.x = g_player[p].ps->pos.x;
-                            g_player[p].ps->opos.y = g_player[p].ps->pos.y;
+                            g_playerSpawnPoints[p].ox += m;
+                            g_playerSpawnPoints[p].oy += x;
                         }
-                        if (sprite[g_player[p].ps->i].extra <= 0)
+
+                        if (s->sectnum == sprite[g_player[p].ps->i].sectnum
+#ifdef YAX_ENABLE
+                                || (t[9]>=0 && t[9] == sprite[g_player[p].ps->i].sectnum)
+#endif
+                            )
                         {
-                            sprite[g_player[p].ps->i].x = g_player[p].ps->pos.x;
-                            sprite[g_player[p].ps->i].y = g_player[p].ps->pos.y;
+                            rotatepoint(s->x,s->y,g_player[p].ps->pos.x,g_player[p].ps->pos.y,q,&g_player[p].ps->pos.x,&g_player[p].ps->pos.y);
+
+                            g_player[p].ps->pos.x += m;
+                            g_player[p].ps->pos.y += x;
+
+                            g_player[p].ps->bobposx += m;
+                            g_player[p].ps->bobposy += x;
+
+                            g_player[p].ps->ang += q;
+
+                            if (g_netServer || numplayers > 1)
+                            {
+                                g_player[p].ps->opos.x = g_player[p].ps->pos.x;
+                                g_player[p].ps->opos.y = g_player[p].ps->pos.y;
+                            }
+                            if (sprite[g_player[p].ps->i].extra <= 0)
+                            {
+                                sprite[g_player[p].ps->i].x = g_player[p].ps->pos.x;
+                                sprite[g_player[p].ps->i].y = g_player[p].ps->pos.y;
+                            }
                         }
                     }
                 }
+
                 j = headspritesect[s->sectnum];
                 while (j >= 0)
                 {
@@ -5811,6 +5828,16 @@ ACTOR_STATIC void G_MoveEffectors(void)   //STATNUM 3
                         }
                     }
                     j = nextspritesect[j];
+#ifdef YAX_ENABLE
+                    if (j < 0)
+                    {
+                        if (t[9]>=0 && firstrun)
+                        {
+                            firstrun = 0;
+                            j = headspritesect[t[9]];
+                        }
+                    }
+#endif
                 }
 
                 A_MoveSector(i);
@@ -6526,6 +6553,11 @@ ACTOR_STATIC void G_MoveEffectors(void)   //STATNUM 3
         case 13:
             if (t[2])
             {
+                // t[0]: ceiling z
+                // t[1]: floor z
+                // s->owner: 1 if affect ceiling, 0 if affect floor
+                // t[3]: 1 if ceiling was parallaxed at premap, 0 else
+
                 j = (SP<<5)|1;
 
                 if (s->ang == 512)
@@ -6552,7 +6584,27 @@ ACTOR_STATIC void G_MoveEffectors(void)   //STATNUM 3
                         sc->ceilingz += ksgn(t[0]-sc->ceilingz)*j;
                     sc->ceilingz = t[0];
                 }
+#ifdef YAX_ENABLE
+                if (s->ang == 512)
+                {
+                    int16_t cf=!s->owner, bn=yax_getbunch(sc-sector, cf);
+                    int32_t jj, daz=SECTORFLD(sc-sector,z, cf);
 
+                    if (bn >= 0)
+                    {
+                        for (SECTORS_OF_BUNCH(bn, cf, jj))
+                        {
+                            SECTORFLD(jj,z, cf) = daz;
+                            SECTORFLD(jj,stat, cf) &= ~(128+256 + 512+2048);
+                        }
+                        for (SECTORS_OF_BUNCH(bn, !cf, jj))
+                        {
+                            SECTORFLD(jj,z, !cf) = daz;
+                            SECTORFLD(jj,stat, !cf) &= ~(128+256 + 512+2048);
+                        }
+                    }
+                }
+#endif
                 if (t[3] == 1)
                 {
                     //Change the shades
diff --git a/polymer/eduke32/source/game.c b/polymer/eduke32/source/game.c
index ee8072b69..d2ae60ca6 100644
--- a/polymer/eduke32/source/game.c
+++ b/polymer/eduke32/source/game.c
@@ -5212,6 +5212,28 @@ int32_t A_Spawn(int32_t j, int32_t pn)
                         sector[sect].ceilingz = sp->z;
                     else
                         sector[sect].floorz = sp->z;
+#ifdef YAX_ENABLE
+                    {
+                        int16_t cf=!sp->owner, bn=yax_getbunch(sect, cf);
+                        int32_t jj, daz=SECTORFLD(sect,z, cf);
+
+                        if (bn >= 0)
+                        {
+                            for (SECTORS_OF_BUNCH(bn, cf, jj))
+                            {
+                                SECTORFLD(jj,z, cf) = daz;
+                                SECTORFLD(jj,stat, cf) &= ~256;
+                                SECTORFLD(jj,stat, cf) |= 128 + 512+2048;
+                            }
+                            for (SECTORS_OF_BUNCH(bn, !cf, jj))
+                            {
+                                SECTORFLD(jj,z, !cf) = daz;
+                                SECTORFLD(jj,stat, !cf) &= ~256;
+                                SECTORFLD(jj,stat, !cf) |= 128 + 512+2048;
+                            }
+                        }
+                    }
+#endif
                 }
                 else
                     sector[sect].ceilingz = sector[sect].floorz = sp->z;
@@ -5422,7 +5444,6 @@ int32_t A_Spawn(int32_t j, int32_t pn)
             case 16://That rotating blocker reactor thing
             case 26://ESCELATOR
             case 30://No rotational subways
-
                 if (sp->lotag == 0)
                 {
                     if (sector[sect].lotag == 30)
@@ -5477,9 +5498,12 @@ int32_t A_Spawn(int32_t j, int32_t pn)
                         G_GameExit(tempbuf);
                     }
                 }
+
                 if (sp->lotag == 30 || sp->lotag == 6 || sp->lotag == 14 || sp->lotag == 5)
                 {
-
+#ifdef YAX_ENABLE
+                    int32_t outerwall=-1;
+#endif
                     startwall = sector[sect].wallptr;
                     endwall = startwall+sector[sect].wallnum;
 
@@ -5497,12 +5521,28 @@ int32_t A_Spawn(int32_t j, int32_t pn)
                                 sector[ wall[ s ].nextsector].hitag == 0 &&
                                 sector[ wall[ s ].nextsector].lotag < 3)
                         {
+#ifdef YAX_ENABLE
+                            outerwall = wall[s].nextwall;
+#endif
                             s = wall[s].nextsector;
                             j = 1;
                             break;
                         }
                     }
+#ifdef YAX_ENABLE
+                    actor[i].t_data[9] = -1;
 
+                    if (outerwall >= 0)
+                    {
+                        int32_t upperwall = yax_getnextwall(outerwall, YAX_CEILING);
+
+                        if (upperwall>=0 && wall[upperwall].nextsector>=0)
+                        {
+                            Sect_SetInterpolation(wall[upperwall].nextsector);
+                            actor[i].t_data[9] = wall[upperwall].nextsector;
+                        }
+                    }
+#endif
                     if (j == 0)
                     {
                         Bsprintf(tempbuf,"Subway found no zero'd sectors with locators\nat (%d,%d).\n",sp->x,sp->y);