The "must have" PC games (Since 2001)
I'm not sure why the best gaming platform was left out of the fun, but here are the must have PC exclusives during this console generation:
Age of Mythology
Age of Wonders
Aliens vs. Predator 2
Baldur's Gate II
Battlefield 1942
Battlefield 2
Black & White
Clive Barker's Undying
Command & Conquer Generals
Dark Age of Camelot
Far Cry (until Xbox butchering is released)
Freedom Force 1-2
Guild Wars
Half-Life 2
Neverwinter Nights
No One Lives Forever 2
Painkiller
Rise of Nations
Rome: Total War
Serious Sam: 2nd Encounter
Wizardry 8
WarCraft III
World of Warcraft
That's 24, second to the PS2 over that span.