var load_level

...

function level_event()
{
	load_level = 1;
	if(load_level == 1)
	{
		if(level < 4 && level != 0) //3 is the maximum level created
		{
			level += 1;
			if(level == 1)
			{
				level_load("thruster1.wmb");
				wait(3);
			}
			if(level == 2)
			{
				level_load("thruster2.wmb");
				wait(3);
			}
			if(level == 3)
			{
				level_load("thruster3.wmb");
				wait(3);
			}
		}
		else
		{
			//player x/z -385,-183
			level_load("thruster.wmb");
			level = 1;	
		}
		if(level == 0)
		{
			level_load("thruster.wmb");
			level += 1;		
		}
		load_level = 0; 
	}
}
action colider()
{
	my.emask |= ENABLE_IMPACT;
	my.event = impact_event;
	set(my,POLYGON);
}



function main()
{
  ...
  level_event();
  ...
}

function level_event(STRING* levelname)
{
	str_cat(levelname, ".wmb");
	level_load(levelname);
	wait(3);
	str_cmp(levelname, "");
}
action colider()
{
	my.emask |= ENABLE_IMPACT;
	my.event = impact_event;
	set(my,POLYGON);
}



function main()
{
	...
	level_event("Leveldatei");  // call level without "*.wmb" ending
	...
}