Penguins may look cute, but they're organized, persistent, and well-armed! Defeat these would-be conquerors by carefully placing tower defenses along their route. Watch your budget though, you'll need to be strategic to get the most fire-power for your money. Each penguin unit you destroy will refill your coffers so you can afford to buy defenses and upgrades. Defeat all the waves in a level to unlock the next level. Good luck, the fate of the earth rests with you!