Now on Steam for like $7.50! Fun little game. Basically the basic conceit of
Audiosurf grafted onto the gameplay of
Geometry Wars. Essentially you have your little flyer dude with a spray weapon not unlike the sort in
Geometry Wars. However, the strength of your weapons against enemies is dependent on two things - the volume of the music and your weapon power, both of which are augmented by pick-up. Thus volume starts a little muted and then gets increased by pick-ups, thus increasing the power of your weapons. If the music is loud and energetic, your weapons will be relatively more powerful than if you were playing in an ambient track, but enemies will be more frequent and weapon power pickups will be less frequent. Likewise, if there's a lull in the song you might find yourself less equipped to deal with threats. You also gain point multipliers by going an extended period of time without firing your weapon - this makes playing in an ambient song a little less useless, as you can still play dodgeball with level objects.
The game seems dynamic enough at this time as far as how the game interacts with music, but the actual dogfighting gameplay is a little lackluster since there are relatively few types of enemies - 4 common enemy ships by my count, plus asteroids and the occasional "boss battle" (if you've played a conventional Raptor / Rez type game, you've run into them before). The difficulty of the game is also enhanced by overpowering visual feedback, similar to later levels of
Geometry Wars - so much is going on that it becomes difficult to tell where things are. Luckily there is an easy difficulty for beginners.

Beat hazard. Anyone play it? I'm sure there are scoreboard sorts of things but I haven't encountered any yet - the UI is kind of a mess, to be honest.