Sonic X-Treme

Why oh why did SEGA not finish this? This could have saved the Saturn. (edit.. No. Saved is going a bit far. Besides, if the Saturn was "saved" would the Dreamcast exist as we know it, would Soul Calibur get the amazing DC port? Would Jet Set/Grind Radio, Phantasy Star Online, or Seaman ever see the light of day?)

Crazy Taxi would probably be a footnote judging from the awful Acclaim ports.

Then again, Capcom's 4 Meg RAM Cart and localized fighting games could have done the job as well.