Wow, this is better than any of my first attempts in GameMaker. My favorite part was the developer commentary, it was funny and insightful. The gameplay ideas you discussed sounded good. I can imagine some neat puzzles that involve managing your size/health/ammo. The music selection was also nice, I was jamming out the whole time I was playing. I got stuck in the "monster" room 3 for a bit by becoming the wrong size, but was able to eventually finish the whole game. Good job!