Systems:
TurboDuo
TurboGrafx-16 core, "hacked" for composite output
TurboGrafx-16 + CD add-on, complete
SuperGrafx + RAU-30 + CD-ROM^2, the biggest system EVER CREATED.
PCE GT (Japanese TurboExpress)
TurboGrafx-CD System Card (2.0)
Super CD System Card (3.0)
Arcade Card Pro
Tennokoe Bank
US region:
Aero Blasters
Air Zonk
Alien Crush
Beyond Shadowgate
Bonk's Adventure
Bonk's Revenge
Bonk 3: Bonk's Big Adventure
Bomberman
Bravoman
Bubble Bobble III: Parasol Stars
Buster Bros.
Champions Forever Boxing
China Warrior
Cotton
Darkwing Duck
Dead Moon
Deep Blue
Devil's Crush
Dragon Spirit
Dungeon Explorer
Dungeon Explorer II
Fantasy Zone
Final Lap Twin
Forgotton Worlds
Galaga '90
Gate of Thunder
Gunhed (Blazing Lazers)
Implode
Impossamole
Keith Courage in Alpha Zones x 5,469
King of Casino
Legendary Axe
Legendary Axe II
Lords of Thunder
Night Creatures
Ninja Spirit
Ordyne
Pac-Land
Psychosis
Riot Zone
Shape Shifter
Sidearms: Hyperdyne
Sinistron
Space Harrier
Splash Lake
Splatterhouse
Terraforming
Valis III
Victory Run
Vigilante
Wonderboy III: Monster Lair
Wonderboy/Dragon's Curse
Ys I & Ys II
Ys III: Wanderers from Ys
Japan region:
Afterburner II
Altered Beast
Anearth Fantasy Stories
Art of Fighting
Batman
Blodia
Bonk's Adventure (PC Genjin)
Bonk's Revenge (PC Genjin 2)
Bomberman '93
Bomberman '94 Battle/Denden no Den
Bomberman '94
Bubble Bobble II: Rainbow Islands
Darius
Dragon Spirit
Castlevania/Dracula X
Cyber Dodgeball
Far East of Eden: Kabuki Klash (or whatever)
Fatal Fury 2
Fatal Fury Special
Full Metal Force/Mad Stalker
Galaga '88
Gradius
Gradius II: Ambition of Gofer
Final Soldier
Hatris
Kung Fu (China Warrior)
Liquid Kids
MotoRoader II
Motteke Tamago (CD-R)
Mr. Heli
Out Run
Panic Bomber
Parodius
Psychic Storm
R-Type I/II carts
R-Type (Complete CD)
Salamander
Sapphire ("aftermarket" version)
Space Invaders
Shockman 3 (or whatever)
Street Figher II: Champion Edition
Wonderboy/New Adventure Island/whatever the Japanese name is
Wonderboy in Monster Land
World Heroes 2
Ys IV - Dawn of Ys
SuperGrafx:
1941
Aldynes (no cardboard box)
Battle Ace
Darius Plus
Ghouls 'n Ghosts
King Granzort
That should be most of them. That's everything in the cabinet next to me plus a few from memory that are in the other room. There might be a few more. I have multiple copies of some games, and still others I own in both US and JP formats (for play on the handheld). All games are complete and original unless noted otherwise. SuperGrafx games include cardboard box/sleeve. I guess I won't include my PC-FX stuff since that's not specified in the thread heading... Oh, and last but not least:
Super HuCard (CD-R)
some demo CD-R's, and a SuperGrafx demo or two