In this tower defence game your goal is to last though the rounds while killing off the creeps that come out. You have the option of choosing many different types of towers and different upgrades. Select a map from the list, click on Load Map then select and construct your towers along the path. When you are ready press Send the Vectoids at the top of the screen. When you have eliminated the first wave you can build some more towers and/or upgrade existing ones. Press Send the Vectoids again to release the next wave.