I guess I can go by console too. For this list I wont count homebrews.
These are the games I can think of off the top of my head.
NINTENDONES - Little Samson
SNES - Hagane
N64 - Clayfighter Sculptor's Cut
GC - Gotcha Force
Wii - My Horse & Me: Riding for Gold
Wii U - Devils Third
GB - Exodus, Joshua or Mega Man V
GBC - Shantae
GBA - Castlevania Aria of Sorrow (i guess)
NDS - Diamond Trust of London
3DS - Cave Story 3D (with cover) or Fire Emblem Fates Special Edition
FAM - Rodland?
SFAM - The three SM Chokyoshi Hitomi games
SEGASMS - Power Strike
GEN - M.U.S.H.A.
SCD - Keio Flying Squadron
32X - Kolibri (i guess)
SAT - Panzer Dragoon Saga
DC - Project Justice
GG - Power Strike 2 (EU)
SONYPS1 - Suikoden II or The Misadventures of Tron Bonnie
PS2 - Rule of Rose
PS3 - Class of Heroes 2G
PS4 - (any of the Limited Run Games I own)
PSP - Class of Heroes 2
VITA - (Any of the limited run games I own)
MICROSOFTXB - Jurassic Park: Operation Genesis
XB360 - Culdcept? Operation Darkness?
XBone - Fallout 4 Pip Boy Edition?
ATARI2600 - Berenstain Bears (sealed)
5200 - Sports Goofy & Looney Tunes Hotel (2 original prototype games never released)
7800 - Ninja Golf or Midnight Mutants
JAG - Missile Command 3D?
LYNX - Double Dragon? (Atariage rated it a 7 rarity)
OTHERODY2 - Power Lords
ASTROCADE - Sneaky Snake
INTV - Diner
CV - Campaign '84
3DO - Any of the "adult" titiles; Plumper's Don't Wear Ties, Sex, The Coven etc
CDi - Link the Faces of Evil?
AES - Ninja Masters
NeoCD - Magican Lord
MVS - Prehistoric Isle 2
T16 - Bonk 3
T16CD - Dynastic Hero
I might have something "rarer" then whats on this list, but this is what I could think of.
There's other oddball consoles I could list, but most would say (anything on this system is rare) lol