Recently I touched on some game background, concepts and some visuals. Now, I think I should describe the basics of the game.

Your goal is to stop the enemy balls from reaching the bottom of the screen. In the vein of many tower defense games, you must purchase and build towers to shoot at the incoming enemies. Unlike many tower defense games, there is contact between the enemies and your towers. If the balls impact your tower, the tower takes some damage. If you take too much damage, the tower is destroyed. The tower provides an obstacle so the balls can't reach the bottom of the screen.

When you destroy a ball, you usually get more money to buy and upgrade towers. Upgrading a tower gives it more firepower and makes it more durable. It is usually more cost effective to upgrade instead of building a new tower. If you destroy all the incoming balls before all lives are lost, you win the level.