In this game you control a soldier from the future named Adam. In his time humanity is almost extinct, due to continuous invasions from aliens that passed by earth every 25 years starting 100 years ago. Adam and his associate Daisy travel back in time to each of the periods that the aliens visited earth in in order to stop them and save the future of mankind.

The camera can be controlled to give the player a third person over the shoulder perspective for accurate shooting, or a birds eye view. One of the biggest features is the large amount of vehicles from each time period that can be commandeered. These include mini vans, tanks, motor boats, and even fighter jets and helicopters.

Each time period has a very large map, divided into zones which must all be clear before being able to fight the giant alien boss of that time period. The exit of each zone is guarded by a big alien processor that sends outthe "harvesting waves" which you will encounter while traveling through the zones, mainly in the many villages. These harvesting waves will attempt to destroy buildings and collect humans for food. If too many humans are "harvested" far more dangerous aliens will start hunting you down and if too many civilians are lost the game will end.
Very often, you will have to help the natives in order to progress through the zones.