For some reason the custom tiles and music didn't work on my end. Not sure why. I have the assets folder in my Documents/VVVVVV folder, so I'm pretty sure they're in the right place. EDIT: Oh, I have to place the contents of the folder in VVVVVV for them to work. It might be worth specifying that better in the readme.
Awesome level, by the way. A bit of an issue, though. If I killed myself in the room with the rapidly changing title, I was no longer able to complete the level. I assume because the warp script as you leave only activates once? Actually, on second thought, it just isn't activating for some reason? Or is there even a warp script? Do I just need to leave the room at the right time?
EDIT 2: Yep, looks like I just needed to leave the room at the right time.