Ok, besides what I said before, maybe I should also say other things.
I don't know what you exactly want from this game, but sometimes the levels are repeated and it can make the game pretty boring, if you want to make better randomly generated levels, there you have Spelunky classic, it's free and open-source, was also made with Game Maker and the levels of the game are randomly generated maybe if you want you can learn something about it, I guess.