Defend the Earth from invading UFOs. Aliens are invading our earth and it is up to you to defend an important nuclear factory. Buy cannons, train new defenders and tell them what to do.
Choose your antibiotics wisely to fight off the infections and save your patient. A fun way to relax and without you knowing it, you'll maybe even learn something useful.
Create a maze out of your towers to defend against 49 levels of advancing creeps. Five different towers with five Upgrades each including distinctive elite towers.
Defend against the robo-bugs that are trying to take over your base. Unlock and upgrade new areas and special weapons. Collect enough exp points to get more powerful weapons.
