Dexter has created the ultimate invention, the Clone-o-matic, but his older sister Dee Dee has meddled again and accidentally cloned herself. Now Dexter's laboratory is infested with several mini-Dee Dee clones bent on destroying Dexter's experiments. Players must help Dexter catch the clones, put his lab back to normal, and restore unity to Dee Dee's selfhood before Mom announces dinner.

In the game, players will battle against hordes of bizarre enemies such as robots, aliens, carnivorous plants, slime monsters, and chemical mutants, and will enjoy extensive gameplay with more than 70 challenges and eight different halls in Dexter's laboratory, including Aviation, Robotics, Bio-organics, and Failed Experiments. Players will beat the bad guys with weapons such as the ray gun, laser gun, weed killer, splurge gun, and stun mines.