The game takes standard science-fiction plotlines about evil aliens (Who are, as always, giant bugs) invading Earth for the sole purpose of eating us. As it turns out, humans are actually just crops that were planted in the Earth millions of years ago, and now mankind is ripe for the picking. The bugs travel through different times to attack, and it's up to one surviving genetically enhanced soldier to save the planet.
Playing the game consists of wandering around town, talking to residents like in an RPG, examining whatever you want, and getting into any vehicles around to take out the alien bugs. Other than saving villagers from the aliens, there are objectives such as extinguishing fires in a firetruck, or solving puzzles. Otherwise, there's a lot of driving & shooting to be done.