The plot involves Mandark taking over control of Dexter's lab. Dexter has to find a way to regain control of his laboratory.
Dexter's Laboratory: Mandark's Lab? consists of a series of mini-games based off of various episodes of the cartoon. The mini games feature various genres, such as first-person shooter and racing. Outside of the mini-games, Dexter walks around a 3D version of his house and laboratory looking for objectives.
This game provides examples of:
- Antagonist Title: Mandark's Lab?
- Dance-Off: The first mini-game is a rhythm game that involves Dexter and Dee Dee having a dance off.
- Expressive Hair: Dee Dee's pigtail curve downwards when she loses in the first mini game.
- "Get Back Here!" Boss: "What's Buggin Dexter?" involves Dexter having to chase down a computer bug and hit it with a flyswatter.
- Girls Have Cooties: Dexter must venture into Dee Dee's room. It's filled with cooties, so the player must first go through a first-person mini-game where he sprays the cooties dead.
- Hub Level: Between each mini-game, Dexter has to explore different portions of his house and lab.
- Mini Game Game: The primary focus of the game are the eight mini-games.
- Overnight Age-Up: At one point in the story, Mandark turns Dexter into an old man using Dexter's own aging ray, and the following portion of the game involves trying to find a way to turn back to his younger self.
- Racing Minigame: One of the minigames is based off of the episode "Mock 5". In it, Dexter must win a soap box derby.
- Rail Shooter: "Cootie Call" and "Dexter Dodgeball" both involve aiming and shooting at targets, albeit with slightly different controls.