The gang is at it again! This time, Scooby Doo Mystery Mayhem must stop an evil business tycoon who has used a device called the Tome of Doom and release monsters from another dimension to distract the gang from what is going on. They must grab the Tome and send the monsters back to where they came before it's too late.
The player takes control of Shaggy and Scooby, with the ability to switch between the two, each with their own special abilities to set traps and capture monsters, and wearing disguises to sneak past them as well. The gameplay is mostly consisted of puzzle-solving, such as moving objects into certain spots to open doors.
Players can explore different environments, including a movie set, The Wild West, a bayou, and a laboratory. The game features the actual voices of the Scooby Doo cartoons and includes artwork and stills of the shows.