There's a fascinating topic over at the rllmukforum in which people are discussing video games that never actually made it to the store shelf.  There's some long forgotten titles being tossed about and some interesting screenshots of early beta versions of games that would eventually end up dead and unfinished.  Marvel at Resident Evil for Game Boy Color, be unimpressed by Freak Boy for Nintendo 64, lament over the demise of Air NiGHTS for the Sega Saturn (with real 3D motion sensor technology), and wonder what Super Mario FX was like when it was considered for the Super NES before it became Super Mario 64.  There's also plenty of talk on games that became other games, such as Dinosaur Planet evolving into Star Fox Adventures, Wave Race 64 ditching its F-Zero connection and becoming a jet-ski game, and the spin-off sequel Diddy Kong Pilot undergoing a makeover after the Nintendo/Rare breakup to become the impressive motion sensorized Banjo-Kazoomie with its 3D voxel engine that was eventually stripped down to become Banjo Pilot.

It's always interesting to see how games evolve and change during development and how some games go through many revisions before reaching a final production version.  Remember the original Kirby's Air Ride for the N64 with its random levels?  Then there's the sad fate of games that are shaping up to be impressive but fall apart when a publisher goes under or an idea is declared unprofitable by the marketing department.  So many horrible games are released every year and yet intriguing titles like Donkey Kong Plus or Dead Phoenix land on the side of the road like yesterday's trash.