Hey, DraconicSyntax! Thanks for your reply. (I'd overseen it earlier, I guess. My bad. I'm not much used to this "tree"-forum format.)
Well, an additional question of mine: Wouldn't it be possible to compile the game with an older version of that GameMaker (to make it useable on older systems) or does the newer GameMaker include some essential features used in the game?
(Again, sorry for my possibly quirky English, for it's not my native language.)