Space Thieves - Build towers to protect our woolly friends from evil sheep-eating aliens. Choose a strategy to defeat all incoming UFOs and stop them from taking sheep to their mothership. The enemy AI will try to analyze the situation and try to make their way through your defenses using different methods. Play this tower defence game by using your mouse cursor and the left mouse button. Click on existing towers, then on the smaller buttons located right, to apply upgrades to it.