A może po prostu:
Create:
global.coll=1
for(i=0;i<instance_number(obj_wall);i+=1)
{
if(global.coll=1)
{
coll=0
if(place_meeting(x-32,y,obj_wall))coll+=1
if(place_meeting(x+32,y,obj_wall))coll+=1
if(place_meeting(x,y-32,obj_wall))coll+=1
if(place_meeting(x,y+32,obj_wall))coll+=1
if(coll<2)global.coll=0
}
}