Index: exec.c
==================================================================
--- exec.c
+++ exec.c
@@ -25,10 +25,11 @@
 Uint32 firstobj=VOIDLINK;
 Uint32 lastobj=VOIDLINK;
 Uint32 playfield[64*64];
 Uint8 pfwidth,pfheight;
 Sint8 gameover,key_ignored;
+Uint8 generation_number_inc;
 
 typedef struct {
   Uint16 msg;
   Uint32 from;
   Value arg1,arg2,arg3;
@@ -83,10 +84,15 @@
   Object*o=0;
   if(!c || !cl || cl->cflags&(CF_GROUP|CF_NOCLASS2)) goto bad;
   o=calloc(1,sizeof(Object)+cl->uservars*sizeof(Value));
   if(!o) fatal("Allocation failed\n");
   o->class=c;
+  if(generation_number_inc) {
+    generation_number_inc=0;
+    ++generation_number;
+    if(generation_number<=TY_MAXTYPE) goto bad;
+  }
   o->generation=generation_number;
 #define C(x) o->x=cl->x;
   C(height) C(weight) C(climb) C(density) C(volume) C(strength) C(arrivals) C(departures) C(temperature)
   C(shape) C(shovable) C(oflags)
   C(sharp[0]) C(sharp[1]) C(sharp[2]) C(sharp[3])
@@ -118,10 +124,26 @@
   return n;
   bad:
   free(o);
   return VOIDLINK;
 }
+
+void objtrash(Uint32 n) {
+  Object*o=objects[n];
+  if(!o) return;
+  if(o->down==VOIDLINK) playfield[o->x+o->y*64-65]=o->up;
+  else objects[o->down]->up=o->up;
+  if(o->up!=VOIDLINK) objects[o->up]->down=o->down;
+  o->down=o->up=VOIDLINK;
+  if(firstobj==n) firstobj=o->next;
+  if(lastobj==n) lastobj=o->prev;
+  if(o->prev) objects[o->prev]->next=o->next;
+  if(o->next) objects[o->next]->prev=o->prev;
+  free(o);
+  objects[n]=0;
+  generation_number_inc=1;
+}
 
 static inline int v_bool(Value v) {
   switch(v.t) {
     case TY_NUMBER: return v.u!=0;
     case TY_SOUND: case TY_USOUND: Throw("Cannot convert sound to boolean");
@@ -219,17 +241,29 @@
   objects=0;
   gameover=0;
 }
 
 const char*execute_turn(int key) {
-  // Set key=0 for initialization
   if(setjmp(my_env)) return my_error;
   changed=0;
   key_ignored=0;
   lastimage_processing=0;
   vstackptr=0;
   
   if(key_ignored && changed) return "Invalid use of IgnoreKey";
   
   if(key_ignored && changed) return "Invalid use of IgnoreKey";
+  if(generation_number<=TY_MAXTYPE) return "Too many generations of objects";
+  return 0;
+}
+
+const char*init_level(void) {
+  if(setjmp(my_env)) return my_error;
+  gameover=0;
+  changed=0;
+  key_ignored=0;
+  lastimage_processing=0;
+  vstackptr=0;
+  
+  if(generation_number<=TY_MAXTYPE) return "Too many generations of objects";
   return 0;
 }

Index: heromesh.h
==================================================================
--- heromesh.h
+++ heromesh.h
@@ -191,16 +191,19 @@
 extern Value globals[0x800];
 extern Uint32 firstobj,lastobj;
 extern Uint32 playfield[64*64];
 extern Uint8 pfwidth,pfheight;
 extern Sint8 gameover,key_ignored;
+extern Uint8 generation_number_inc;
 
 void pfunlink(Uint32 n);
 void pflink(Uint32 n);
 Uint32 objalloc(Uint16 c);
+void objtrash(Uint32 n);
 void annihilate(void);
 const char*execute_turn(int key);
+const char*init_level(void);
 
 // == game ==
 
 void run_game(void);
 

Index: main.c
==================================================================
--- main.c
+++ main.c
@@ -214,10 +214,11 @@
   if(!buf) return "Cannot find level";
   free(level_title);
   level_title=0;
   annihilate();
   generation_number=TY_MAXTYPE+1;
+  generation_number_inc=0;
   level_version=p[0]|(p[1]<<8);
   level_code=p[2]|(p[3]<<8);
   p+=4;
   pfwidth=(*p++&63)+1;
   pfheight=(*p++&63)+1;