In Astrosmash, the player controls a laser cannon at the bottom of the screen; the goal is to earn as many points as possible by destroying the various incoming meteors, bombs, and other objects. Points are earned for destroying objects, while points are lost for letting them get past the player. Meteors are the most common item needed to defend against. They come in various sizes and colors, and some even split into two smaller meteors when shot.
Mixed in with the meteors are white spinning bombs. While letting a meteor get past, the player will only lower the score; the player have to shoot the spinners. If one gets past, the player will lose a life. On the more difficult levels, UFOs and guided missiles will also appear occasionally and attempt to destroy the player's cannon.
If trapped in a hopeless situation, the cannon may enter hyperspace and be instantly transported to a different location on the screen. Just be careful, sometimes the player may be transported to a situation worse than the one the player left! The game ends when all of laser canons have been destroyed.