Advent Children? What if Square hadn't defected to the PlayStation? What if Aeris didn't have to die and instead was real and we were in love and got married?
Of course, only slightly less popular is the "What if Final Fantasy VII came out ten years earlier and was 8-bit" scenario. We're pretty sure someone already did the actual work of porting the game over to the Famicom (thanks, Shenzhen Nanjing Technology Co, Ltd!) but in case you missed that, take a gander at Martin Barreby's non-interactive reimagining after the break. Sure, some of the art looks like it's cut from a fanfic and the gameplay actually looks worse than 1987's Final Fantasy 1, but it's "just a small project with not that much effort put into it" says Barreby, so lay off.
Next: What if Cloud's sword and hair were subject to the same laws of gravity that we are?