love the concept and it plays well, but I think it needs one or two things to spice up the core loop (like the alien ships in asteroids or the power-ups in breakout).
I'd like to see a black-and-white mode for the highest possible contrast, and I'm not sure if there are minor frame hitches, but I think there might be. Cool game, thanks for making it!!
Haven't had a chance to look into multiplayer much but it seems to work all right.
(current high score holder at 291960, although screenshots imply you've gotten much higher)