i'll stick to 8bit nes

blaster master 2
chase hq
earthbound
exerion 2
f-1 hero
f-1 roc
fastest lap
final fantasy II
galaxian
grand prix
gun.smoke 2
helicopter
hero quest
hyper zone
kirby's dream land
kung fu 2
labyrinth
Mike Tyson Intergalactic Power Punch
Miner 2049'er
R - Type
RailRoad Tycoon
The Return of Donkey Kong
Sim City
The Speed Rumbler
Streetfighter II
Super Hang On
Super Mario 4
Terminator 2 : The Arcade Game

and most of the other unreleased nintendo, capcom, and konami titles not mentioned here.

i think this would be a good topic to discuss on the retro league podcast.. if it hasn't already

Super Mario FX and Halo DS

I'm going to go with Dactyl Joust for the Jaguar CD. There was a demo video of it but a prototype copy has never leaked or magically appeared on ebay. It apparently was playable but not near completion.

For years I've wanted to play Resident Evil 1.5 (scrapped version of Resident Evil 2 that was almost completed).

I had no idea there was a Street Fighter II in the works for the NES (officially). I played Star Fox 2 recently on an emulator and understand why it may not have been released. It had a lot of good ideas but I think they were executed poorly. Taking those ideas over to Star Fox 64 was a great move in my opinion.

Sonic Crackers! LOL

Biohazard 1.5
That Lufia game that was supposed to be on PSX. (I think it was called Ruins Chasers?)
Lunar 3 (Hinted at for years, might of been just Victor Ireland BSing though)
Sonic 2 with a fully working Hidden Palace Zone (Who knows if it ever actually existed though...)