Planet Defense is a tower defense style game that requires offensive tactics to win. You control a small ship that can build towers and capture bases. Defend your base from the onslaught of enemy robots to avoid losing, but to win you must capture the enemy's base!

Use W,A,S,D or arrow keys to move your ship around the map. Click on the wrench button in the blue menu bar to access the tower build menu. Select a tower, then select a tile on the map to build that tower. It must be close to your character. Avoid getting hit by the enemies! If you character dies you will lose. Click on the base of a tower (the center of the tile it was built on) to see a dialog with information about that tower. You can also sell or upgrade a tower from this dialog. Build reactor towers on crystals to generate energy. Energy is required to build towers. Destroyed enemies also drop small crystals, move your ship over them to collect extra energy.