Putting these here,
Deus Ex
Thief 1&2
Jagged Alliance 2
Drakan: Order of the Flame
Arcanum
Fallout 1&2
Morrowind (the last ES game that was designed for PC)
Crusader: No Remorse & No Regret
No One Lives Forever 1&2
Duke Nukem (as Baler mentioned,
Blood is the best)
Shadow Warrior
Baldur's Gate 1&2
Icewind Dale
Planescape: Torment
Star Wars: Dark Forces
Tom Clancy: Rainbow Six/Ghost Recon/Rogue Spear
Giants: Citizen Kabuto