Playing as a mixture of Peter, Stewie and Brian you must complete the characters story-like progress in the game. Each character has a separate story to do and each level has objectives to complete in order to move on.

Brian: Brian is accused of impregnating SeaBreeze, a racing dog for which Brian has had a restraining order placed against him. Brian must escape prison and find the real father of SeaBreeze's puppies. Each level Brian must escape the notice of the other characters and try to clear his name by collecting evidence. To assist you at some points, disguises can be found to help you slip by people without them noticing.

Stewie: After Stewie has his plan thwarted by Bertram, his arch-nemesis, Stewie must find out what Bertram is planning and stop him, I mean, if you're trying to take over the world, you won't want someone else doing it first, right? So equipped with a ray-gun, grapple and mind control beam, make your way through to bertram's hideout via Peter's testicles. Manipulate, destroy, climb and jump your way through the levels to destroy Bertram and what ever he is planning.

Peter: The "Fat man" as Stewie calls him, after sitting for five days straight watching Mr Belvedere on TV, Peter is knocked unconscious by a falling antennae from his roof. After being taken to hospital he is in a state of stupid rage, he thinks Mr Belvedere is trying to kill him and that everyone he meets is an assassin. Equipped with fists, feet and fat, beat up everything you see and make your way through Quahog trying to find Mr Belvedere. As you progress to different locations, watch out for falling objects!!