Planet Smashers is a vertically scrolling shooter. Enemy ships descend from the top of the screen. You can move your fighter around the bottom third of the screen. An informational display across the very bottom of the screen shows your score, lives remaining, shields, cloaks and the status of the Earth Shield.

Power ups are gained by shooting alien cargo ships and catching the cargo as it falls to the bottom of the screen. These power ups can improve your weapons, restore your shields, or give you the ability to cloak your ship so it cannot be seen by the aliens.

The cargo ships also drop colored warp capsules that are needed to move to the next level. The player must catch three capsules of specific colors in the correct order to advance to the next level. Boss aliens appear at the end of each level.

The game ends when you have lost all of your ships or the Earth Shield is destroyed. The Earth Shield status decreases each time an alien slips by you.