I've found some nice working isometric demo with working collisions made with game maker.
Because I never really figured out how exactly gm scripts work (on step and everything), I couldn't port it to C2 :/.
I already posted the example in the "game design section" -> here.
Maybe someone who knows GM a little more with some advanced skills could port the game mechanics to C2.
the gmk file -> link
the compiled demo -> link