It's free to download and play around with, and supports any midi file as an input. The catch is that you can't use a keyboard unless it's connected to your computer via midi port. I have a midi-compatible keyboard but don't have a midi cable to try it out. I will be getting one very soon to test it though and will post updates when I do. I imagine it's a pretty fun way to improve your skills at keyboarding and learn how to play some video game music. Link: Synthesia - Have Fun Learning To Play The Piano, Free!
That is fucking amazing. I'm going to give it a whirl tomorrow hopefully. Chris: You don't need a kb for that shit. It's all point-click now.
This game is ridiculously hard. It'd be nice if it had an indicator of what note is going to be played, or a smaller keyboard to focus on instead of all the keys. I guess I should just keep practicing. Right now I can't do anything with it, but I'm a lousy keyboard player. Lowering the speed sort of helps. I tried playing some Final Fantasy / CT music and it's even harder, but I need practice.