I liked this mod. It was funny and fun. The altered title screen music got me laughing before I even started, though the other sped up songs weren't that interesting. The boss theme was cool though.
I thought the final solution to the chest room was clever. I really liked the B@lrog fight. If you were gonna change the tetris room at all, which I know you won't, I'd want you to make the first half harder--you can just stand on top of the first block for a good half the room, which makes the two seconds or so of highly concentrated trial and error at the top more grating. The next room was kinda lame; changing the falling block room from horizontal to vertical just emphasizes the luck aspect, as 90% of the time you're totally safe and the other 5% it's almost undodgable--you're better off just ignoring them entirely and boosting to the top. As for Blocky, I liked him a lot just the way he is, especially the "leveling up your polar star on the 'bats'" part. If you're gonna change it at all, just make the bats stronger, but I don't think he even needs that. If you stop the bats from dropping crystals it'll stop being fun altogether.
edit: I also thought stealing some of misery's dialogue was sorta funny. Also, my money's on the block gun being the bubbler in disguise.