I don't know that I can really list them all off the top of my head, but I'll try.
The computer is the only thing I've got. It shall likely remain this way. So, these are all computer games.
Unreal Tournament 2004
Half-Life
Opposing Force
Blue Shift
Half-Life 2
Guild Wars
Baldur's Gate (Tales of the Sword Coast)
Baldur's Gate II: Shadows of Amn
Baldur's Gate II: Throne of Bhaal
Icewind Dale (Heart of Winter)
Icewind Dale II
Neverwinter Nights (Hordes of the the Underdark)
Lemmings Revolution
Lemmings 3d
Knights of the Old Republic
Knights of the Old Republic II
The Godfather
Magic: The Gathering Online
Commander Keen I, II, III, IV, V, and VI
Lemmings
Duke Nukem I
Duke Nukem II
Hocus Pocus
Crystal Caves I, II, and III
Mystic Towers
Whacky Wheels
Lemmings II: The Tribes
Lemmings: The Chronicles
Koules
Dinosaur Safari
SimTower
SimCity classic
SimCity 2000
SimCity 3000 (Unlimited)
SimCity 4000
Sonic & Knuckles
Sonic the Hedgehog
Sonic the Hedgehog 2
Sonic the Hedgehog 3
Sparkster
Spellbringer
Enchanter
Zork 0
Zork 1
Zork 2
Zork 3
Nibbles
Populous III: The Beginning
Dungeon Lords
Mission Humanity
Railroad Tycoon
Railroad Tycoon II
Zoo Tycoon
Moon Tycoon
Train Simulator
The Sims
The Adventures of Lomax (demo)
Arthur's Knights
Mythical Warriors
Myst
Riven
Tron 2.0
I must be forgetting something. I know I'm forgetting something. Anyhow, I don't really play all of these games right now, but I've played them all at some point for relatively to extremely extended periods of time.