Aside from the performance issues that other people have mentioned, this is quite fun. I've always liked running through a collapsing building or structure of sorts. The urgency to get out as soon as possible makes for quite high energy gameplay, which I'm a big fan of! The pixel art in this game is pretty good too, nice job! I think the movement could be polished up a little bit more though, try experimenting with how you give the player feedback when colliding with things, jumping around, etc. You might be able to add a lot of juice and game feel to this. Anyway, good game and good luck :)