I realize nobody has probably done a thread about this yet! So, now is a better time than any, since it being late and all the rarity of rare games has probably sore by now. I will start off with my two Saturn games, only rarities I actually own.

* Street Fighter Zero 3 *
The infamous, definitive SEGA version of Street Fighter Alpha 3, which I can vouch is pretty dang good. Definitely the gem in my collection for being the most expensive game I own. Has everything too, so I have a pretty solid copy.

* Akumajo Dracula X: Nocturne in the Moonlight *
Finally hit the triple number zone recently, so somewhat rare now. Aside from rarity, it is known for being a horrible port of the PSX classic. Personally, I wish this was the game given more effort since it deserved it. I could have lived with dithering effects if they did them better and slowdowns were, and SHOULD have been all absent since the Saturn is a 2D Beast. But, I still like playing it since it has so much more stuff to do and items to collect and Maria to kick ass with.

I own a loose copy of Battletoads Double Dragon on NES and a complete boxed Doom on Gameboy advance, and Sonic Classics on genesis.
That's about it.

Blue disc Marvel vs Capcom 2 for ps2

i own a blue disk of Casper Sprit Deminsions

I have a couple rare snes games. Sunset riders and captain commando. They're both like 60 bucks each used.

I have the full uncensored version of Thrill Kill and Mortal Kombat II for playstation.

A 100 games in 1 console.

Killer instinct (arcade), super mario bros (pinball machine), chrono trigger, power glove, sega cdx.

some are more rare/available than others, but i'll go by console, and all are loose copies unless otherwise noted:


nes:
bucky o-hare, metal storm (have a handful that go for a lot now, but not sure on rarity, as with the ones i've listed - i think they're more in demand than "rare")


snes:
ninja warriors, castlevania: dracula x, e.v.o. the search for eden, demon's crest, hagane (sfc japan version), ninja gaiden trilogy, earthbound, chrono trigger, metal warriors.

genesis (all have at least hard case/artwork):
alisia dragoon, el viento, cadash, chiki chiki boys, high seas havoc, mega man: the wily wars, alien soldier, golden axe III, skeleton krew, splatterhouse 2 and 3, the punisher, valis and valid III, zero the kamikaze squirrel

saturn:
akumajo dracula x gekka no yaso kyoku (castlevania sotn)
guardian heroes
primal rage (pal)

i have more newer systems/games but this took a while!

great, formatting didn't work