1. Select your character and DIFFiculty level. 2. Move your character around the map to find and collect resources. 3. Use the resources to build defensive structures such as walls and turrets. 4. Place your defensive structures strategically to protect your base from incoming alien Waves. 5. Upgrade your structures to make them stronger and more effective against the aliens. 6. Use your character’s special abilities to help you survive the alien onslaught. 7. Survive as long as possible and achieve the highest score possible.