um, sorry if i dont understand your question, but for the collision detection i use the techniques in the area i said before, and i dont understand the engine part?
if this helps, here is the exact code:
"--- ------ -----] [  ] ] --------- ---→Str1
but i edited the repeat part to look like this
If A=6 and B=1:Goto L
to hopefully get the exit points, but doing this wont let u enter the space exits, so i want to know if there is a different way to do this