Mischief Makers is an action-platformer for the Nintendo 64 developed by Treasure. In the game, the player controls Marina Liteyears, the robotic maid of Professor Theo, who is kidnapped while visiting the planet Clancer. It's up to Marina to save Professor Theo and the people of Clancer from an imperial invasion. One of the first 2D action games on the system, the game received mixed reviews.
On a visit to planet "Clancer," Professor Theo, creator of Marina Liteyears, is kidnapped by the mysterious Empire while Marina is out. Upon realizing that the Professor has been kidnapped, Marina sets out to stop the Empire and rescue the Professor. On her journey, she meets the citizens of Clancer, takes part in a Olympic style mini-game festival, fights agents of the Empire and faces off against the Emperor himself.
The game is a side-scrolling platformer in which Marina's primary abilities are grabbing, shaking, and throwing objects as a means to solve puzzles and defeat enemies. Shaking in particular has a wide range of effects such as causing enemies to drop gems or causing a projectile to grow larger before throwing it back at an enemy.
The game had an unique mechanic involving the ending sequence and the collection of 52 "golden gems," special items that could be obtained by performing special tasks within the game's levels and including shaking certain enemies, projectiles or bits of scenery, beating mini-games in record times or clearing a stage without being hit once in the case of the several boss battles. How much the player is allowed to watch the complete ending depended entirely on how many gems they collected, with each gem adding 3 seconds of viewing time. If there were not enough gems to watch the entire cutscene, the game would interrupt the sequence and urge the player (and Marina) to collect more. If the player collects all of the golden gems, Marina is transformed into a human girl at the very end of the game.
- Marina Liteyears - The main protagonist of the game and the person the player controls. She's trying to rescue Professor Theo.
- Professor Theo - The creator of Marina. He is kidnapped at the very beginning of the game by the Empire.
- Teran - A friendly Clancer wearing a baseball cap. He helps out Marina in a number of ways throughout the game.
- Lunar - One of the Beastector.
- Tarus - One of the Beastector.
- Merco - One of the Beastector.
- Emperor - The mysterious entity that runs the Empire.
Treasure's CEO, Masato Maegawa, has stated that during development there was an average of 12 staff members working on the game. The maximum amount of staff working on the game was 15.