Finished, shelved, and never released — the games that almost were
Star Fox 2 was a complete, fully playable sequel to Star Fox for the SNES that Nintendo finished and then shelved in 1995 to avoid undermining the N64's launch, remaining unreleased for 22 years before appearing on the SNES Classic Mini.
Thrill Kill was a completed four-player PlayStation fighting game featuring extreme violence and sexual content that Electronic Arts refused to publish after acquiring Virgin Interactive, cancelling a finished product weeks before its scheduled release.
Bio Force Ape was a near-complete NES action game by Seta Corporation that was cancelled before release in 1991 and believed lost for two decades before a prototype cartridge was discovered and auctioned in 2010.
Dinosaur Planet was Rare's ambitious N64 action-adventure featuring original characters Sabre and Krystal on a world of warring dinosaur tribes, which Shigeru Miyamoto personally requested be reframed as a Star Fox game, eventually shipping as Star Fox Adventures on GameCube in 2002.
Sonic X-treme was Sega's long-gestating attempt to bring Sonic the Hedgehog into 3D on the Saturn, a project that cycled through multiple engine designs and development crises over three years before being cancelled in 1996, leaving the Saturn as the only Sega platform without a mainline Sonic game.
Castlevania: Resurrection was a 3D Castlevania game in development for the Sega Dreamcast featuring returning protagonist Victor Belmont and new character Sonia Belmont, cancelled by Konami in 2000 after the Dreamcast's commercial trajectory became clear.
The 9 was a near-complete NES action game by Sunsoft — developer of Batman and Blaster Master — that was cancelled as the NES market collapsed in 1993, rediscovered decades later through prototype archaeology, and found to be a polished and playable finished product.
Mother 3 spent nearly six years in development as a Nintendo 64 title before Nintendo cancelled it in 2000 after the game's scope had expanded to unmaintainable scale, eventually shipping on Game Boy Advance in 2006 in a scaled-down form that was never officially localised for Western markets.
The 1997–2001 era of Duke Nukem Forever was 3D Realms' first attempt to sequel Duke Nukem 3D, cycling through two complete engine rebuilds in four years and becoming gaming's most famous development hell before the rights were sold and a different game shipped a decade later.
Airworld was the planned fourth and final chapter of Atari's SwordQuest series — an ambitious multi-game contest offering a $150,000 real-gold prize to the winner — that was never developed after the 1983 video game crash destroyed Atari's finances and ended the contest.