#define _id skill100
var var_bighome_deaths[10];
var var_enemy_count;

action enemy(){
   
   my._id = var_enemy_count;
   var_enemy_count++;
   if(var_bighome_death[my._id]){
      ent_remove(me); //or set dead animation or whatever you're doing
   }
   
   ...
   
   //is dead
   var_bighome_deaths[my._id] = true;
}

void level_choose(level_var){
   var_enemy_count = 0;
   level_load(bighome_level);
}

ACTION enemy
{
	var idtemp;
	var fhandle;
	fhandle=file_open_read("bighome_level.txt");
	id_count+=1;
	my.ids_given=id_count;

	var i=0;
	while (i <= 10)
	{
		if (fhandle)
		{
			idtemp=file_var_read(fhandle);
		}
		if(idtemp==my.ids_given)
		{
			ent_remove(me);
			return;
		}
		i += 1;
		wait(1);
	}
[...]
}

function AI_die() 
{
	proc_kill(1);
	var fhandle;
	fhandle=file_open_append("bighome_level.txt");
	if(fhandle)
	{
		file_var_write(fhandle, my.ids_given);	
	}
	else
	{
		fhandle=file_open_write("bighome_level.txt");
		file_var_write(fhandle,my.ids_given);	
	}
	file_close(fhandle);
[...]
}