The goal of Base Defense is simple, the players city is being attacked by a hail of ballistic missiles. As the commander of regional surface to air missile battery the player must defend as many buildings as possible from enemy missiles. Enemy missiles include MIRVs and even smart bombs that are difficult to shoot down.The player has a limited number of missiles in his missile batteries. A battery becomes useless when it runs of ammunition or is destroyed by an enemy missile. The game inevitably ends when all buildings in the city are destroyed.