Your mission in this turret defense game is to defend the Earth from invading UFOs. Aliens are invading our earth and it is up to you to defend an important nuclear factory. Do this by buying cannons, training new defenders and telling them what to do. You also need to make strategic decision about what cannons you buy and what upgrades you make. Use YOUR MOUSE to control all aspects of the game. I suggest you to read in-game How To Play section to check detailed instructions. Have fun!