Detritus is a cross platform Asteroids in which you shoot asteroids and get powerups! Windows, Linux, Mac OS X 10.2 - Mac OS X 10.12
(Not working on Mac OS X 10.13)Product Description:
Detritus is a fast-paced shoot-em-up strongly based after the old classic Asteroids. Replenish your shield with power-ups and gain new weapons. "Cleaners" appear periodically, so watch out! The keyboard controls should be self-explanatory.
http://www.erif.org/code/detritus/