Monsters, Inc. is a 3D platformer. Players control James P. "Sulley" Sullivan through 8 levels based on environments from the movie, including the scream factory Monsters Incorporated, the streets of Monstropolis, Sulley's apartment, the Himalayas, and more. In each level, the main goals might include picking up one or more special items, or finding the exit. Sulley has to make his way across platforms, ladders and conveyor belts by jumping, climbing, flipping switches and pushing crates around. To attack enemies, Sulley can use his tail to whip opponents. The game has no lives system, so levels can be attempted an unlimited number of times.[3]
Each level also includes a number of collectibles and special tasks. There are 100 discarded screams to pick up; finding a certain percentage of them unlocks mini-game bonus levels. There are also five scream canisters to find and a small challenge involving scaring five mice within a time limit. If both are completed, clips from the movie are unlocked.[3]