Unknown monsters and weird robotic creatures attack the Earth. For some reason, the only ones who can stop the invasion are the three Dinosaurs for Hire: Archie, a tyrannosaurus rex and their leader; the triceratops Lorenzo, lover of fine food, fine wine, and fine clothes, and the one-eyed, unpredictable stegosaurus Reese. Each dino has its own strengths and weaknesses.

You guide the dinosaur of your choice through the platform levels of the game. You are equipped with a gun: tons of enemies will attack you from all the sides, so your best bet will be walking with the fire button pressed down. You can shoot to all the directions and also engage in melee combat when the enemy is too close. Each level has a boss enemy waiting for you in the end. There is also a cooperative two-player mode.