Are you using the free version of GameMaker? What sort of limitations does it have? How is your pixel art Metroidvania tower defense with physics puzzles going?
I bought the Professional edition for $35 during one of the flash sales so I have no experience with the free version, but since since it caps your room and objects count, it's mostly like a demo rather than a full fledged free version (like, say, Unity's).
I went with the Pro edition because it had SVN support, unlimited assets (though Personal has that too) and because it was pretty cheap, really.
As for my game, it's just a sort of Space Invaders clone and I'm drawing programmer art spaceships with no respect for any basic pixelart rules and basically making goofy laser beams and other guns while I discover new stuff about the engine every day.
The purple hue shift ship is meant to resemble the helmet from Fallout 2's enclave power armor a bit
Really, I'm impressed with Game Maker because I feels like the best mix of drag and drop and actual high-level coding I've ever seen, even if the scripting language is pretty basic and the map editor is pretty bad. It seems to be in constant development so they might improve those things, though.
So bottomline, if you're good at programming, you probably will dread GM but for lesser mortals that just enjoy making games and can hold their own with the ifs and the whiles then it seems very much alright.
Also it has cheevos.