The Battle for Earth

A large alien vessel just landed on Earth. They already made a full attack on our communication network, and they disabled our security system. Scientists found out that the reason behind the invasion was an artifact that had long been buried on Earth. The aliens are here to get it because it can be used as a powerful weapon strong enough to destroy the entire planet. It's every man for himself now, and the only thing you can do is kill all the alien soldiers, deactivate all the weapons, and put an end to this madness!