In Astrosmash you control a laser canon at the bottom of the screen; your 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 you. Meteors are the most common item you need to defend yourself 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 you will only lower your score, you have to shoot the spinners. If one gets past, you will lose a life. On the more difficult levels, ufo's and guided missiles will also appear occasionally and attempt to destroy your canon.

The Intellivision game catalog features the exciting caption, "Spin. Blast. And drop into hyperspace to avoid a killer asteroid shower. Power on. Attack computer engaged. Fire a quick burst at the alien antagonists. Got 'em!" The actual package gives a more specific description: "You're in command of a battery of laser guns. You have unlimited ammo and a lot of targets! You can roll up big scores by hitting a spectactular barrage of falling rocks, bombs, guided missiles and attacking UFOs..."