Pokémon Prism is a cancelled Hack Rom of Pokémon Crystal, created by Koolboyman. The storyline elapses in the region of Naljo. It's the sequel of Pokémon Brown, therefore, there are new Elemental Types and new TM's. You can travel to Rijon for a second quest. The Pokédex has 252 Pokemon, including some from each of the first four generations. The game includes new mini-games and plot points in which the player controls a Pokémon.

On December 21, 2016, Nintendo sent a cease & desist order which ended the game's development. However, an anonymous user on 4chan leaked v0.91 (build 0144) of the game, the leaked build is from December 19, 2016.

The current leaked build is fully functional, but is missing certain things from what would have been the finalized version of the game, such as outdated sprites, missing trigger events for trainers, and a post-game mission from Lance that was supposed to have been released in an official future build of the game.