Details regarding a Wii-exclusive game that was in development at Retro Studios have appeared online, which describe it as being similar to Valve's Portal. While the studio is best known for its work on the Metroid Prime series, the developer has tried and branched out into creating other series and games for Nintendo. This can be seen with games like Mario Kart 7 and Donkey Kong Country Returns, though the studio has a history of pitching several other games to Nintendo. These include failed pitches for Zelda spin-offs, such as a tactical strategy RPG known as Heroes of Hyrule.