Jelly Monsters was originally developed as a port of Pac-Man by HAL Laboratory for Commodore Japan, who held the home computer rights for Pac-Man in Japan at the time. When Commodore released it internationally the title was changed to Jelly Monsters, since Atari held the home computer rights for North America.

Commodore’s Jelly Monsters was released in 1981, a year before Atari would release Pac-Man for the 2600. Atari quickly sued Commodore to have the title removed from shelves and won.