I'm not sure what you consider old. Pretty sure these are all games from at least 6+ years ago. Some of them you wont be able to get the full effect on. Like planetside I'm pretty certain does not have servers up for it anymore, and while Nox has a great singleplayer; it's real strength was multiplayer which is basically now only populated by Koreans who have been playing the game for 13 years and will absolutely wreck anyone who's new to the game.
Anyways from my list of PC games that are good:
Arcanum
Alien Versus Predator 2
Command and Conquer
C&C Red Alert
Neverwinter Nights 2 + Mask of the Betrayer
Nox
Planescape Torment
Starcraft
Knights of the Old Republic
Knights of the Old Republic 2
Hitman Blood Money
Deus Ex
Doom
Doom 2
Quake
Quake 2
Fallout
Fallout 2
Fallout Tactics
Company of Heroes
Total Annihilation
The Secret of Monkey Island
Monkey Island 2: LeChuck's Revenge
The Curse of Monkey Island
Ultima 4
Ultima 6
Ultima 7 + Serpents Isle
Ultima 8
Syndicate(1993 Version)
System Shock 2
Theme Hospital
The Longest Journey
The Longest Journey: Dreamfall
Battlefield 1943
Call of Duty(Origional)
Warhammer 40,000: Dawn of War + Expansions
Vampire the Masquerade Bloodlines
Giants Citizen Kabuto
Worms 2
Age of Wonders
Crusader No Regret
Crusader No Remorse
Homeworld 2
X-COM: UFO Defense
Lords of the Realm 2
Half-Life
Half-Life 2 + Episodes
Max Payne
Max Payne 2: The Fall of Max Payne
Hearts of Iron 2
Sid Meier's Pirates!
Space Quest: The Sarien Encounter
Space Quest II: Vohaul's Revenge
Space Quest III: The Pirates of Pestulon
Space Quest IV: Roger Wilco and the Time Rippers
Space Quest V: The Next Mutation
Space Quest 6: The Spinal Frontier
Counterstrike
Warcraft 2
Warcraft 3
IL-2 Sturmovik
Ultima Online
Planetside
also Peasants quest. http://www.homestarrunner.com/disk4of12.html if it counts...
Anyways from my list of PC games that are good:
Arcanum
Alien Versus Predator 2
Command and Conquer
C&C Red Alert
Neverwinter Nights 2 + Mask of the Betrayer
Nox
Planescape Torment
Starcraft
Knights of the Old Republic
Knights of the Old Republic 2
Hitman Blood Money
Deus Ex
Doom
Doom 2
Quake
Quake 2
Fallout
Fallout 2
Fallout Tactics
Company of Heroes
Total Annihilation
The Secret of Monkey Island
Monkey Island 2: LeChuck's Revenge
The Curse of Monkey Island
Ultima 4
Ultima 6
Ultima 7 + Serpents Isle
Ultima 8
Syndicate(1993 Version)
System Shock 2
Theme Hospital
The Longest Journey
The Longest Journey: Dreamfall
Battlefield 1943
Call of Duty(Origional)
Warhammer 40,000: Dawn of War + Expansions
Vampire the Masquerade Bloodlines
Giants Citizen Kabuto
Worms 2
Age of Wonders
Crusader No Regret
Crusader No Remorse
Homeworld 2
X-COM: UFO Defense
Lords of the Realm 2
Half-Life
Half-Life 2 + Episodes
Max Payne
Max Payne 2: The Fall of Max Payne
Hearts of Iron 2
Sid Meier's Pirates!
Space Quest: The Sarien Encounter
Space Quest II: Vohaul's Revenge
Space Quest III: The Pirates of Pestulon
Space Quest IV: Roger Wilco and the Time Rippers
Space Quest V: The Next Mutation
Space Quest 6: The Spinal Frontier
Counterstrike
Warcraft 2
Warcraft 3
IL-2 Sturmovik
Ultima Online
Planetside
also Peasants quest. http://www.homestarrunner.com/disk4of12.html if it counts...