Hello friends, everyone log into your Steam accounts and buy Audiosurf for only $10.
It's a music/puzzle game of sorts. You pick any song you want to play and it generates a level for you, using the beat and the notes and stuff as bumps and curves and blocks and everything. You then either pick up all colored blocks and dodge the gray ones in the Mono mode of you can play any of the other modes which have you sort the colored blocks into groups of 3 or more for points, kinda like a high speed columns.
Here are some videos I took
Ninja Mono mode, pick up colored blocks and dodge grays
http://www.youtube.com/watch?v=jlhBjiP-Doc&feature=user
Pointman Elite mode, scoop up blocks and put them in different columns kinda like Klax.
http://www.youtube.com/watch?v=mrVAOsHbHRI
There is a high score table for each song so you can compete with people around the world.
You can use any song you want provided it's MP3, ogg, mp4, itunes, and I forget what else. Check audio-surf.com for details on that. It turns the song into a level that is always the same. Since you can compete with others online for a high score you can hover over their name on the leaderboard to check out the graph for the song, the song length, and their various bonuses to make sure they aren't playing some totally different version of Beat It or whatever to keep things fair.
The game is only $10 on Steam, and it comes with the Orange Box soundtrack! I've been playing it for a while and it's really fun because it has the best soundtrack of any music game ever.
If you're still not convinced, you can download a demo over steam as well.