I haven't skimmed the entire thread, but if no one has mentioned The Elder Scrolls III: Morrowind, then this has all been for naught.

@Sticky_Pennies said:

• Planescape: Torment
• Quake III Arena
• Dragon Age: Origins
• Half-Life 1 & 2
• Diablo 2
• Deus Ex
• System Shock 2
• Starcraft: Brood War & Starcraft II
• Warcraft III & Frozen Throne (screw that WoW noise.)
• Duke Nukem 3D
• Mechwarrior 2
• Pool of Radiance
• Day of the Tentacle

You need to know your roots.

Edit: Linkified.

Your list was almost perfect, but you missed Morrowind and Gothic 2.

The Witcher 2 is a must if you ask me.

A Brief History of PC Gaming: 1990 - 2010

(right-click-->view image or open in a new tab to see it in full size)

The larger the game image, the more "important" the game. Try Steam or Good Old Games to find legitimate copies of the older stuff.

Killing Floor, Dragon Age Origins, Legend of Grimrock, make sure you pick up Gods and Kings or whatever for Civ V, because it's pretty awesome with that expansion, ArmA 2 Combined Operations, Warhammer 40k Dawn Of War II and friends, and plenty more. Any Valve or Blizzard game is always a decent choice.

@xMrSunshine: Man, people who make that argument are real frustrating. Just use some common sense and things about what they probably mean. I don't think the guy needs to fuckin' play Zork or SimCity2000.

Well, maybe Zork, but that's just because Zork is timeless. But still, you're fucking suggesting ArmA and the older OF games? With ArmA 3 around the corner, you're suggesting the original?

Just be useful and answer the question, don't be that jerk that answers a question like that. It doesn't help the person posting much. If they wanted a list of games with historical value, they would have asked for it.

You are going to have to give more info than that. The PC has been around for 30 years. There are hundreds, if not thousands, of PC exclusives that were at one time or another worth playing. Do you want just modern games that are only on PC or ports of console games that are better on PC or any games that were good on PC ever?

One game that I absolutely loved every minute of that I don't see listed: Vampire: The Masquerade - Bloodlines

Play through Deus Ex, it definitely is one of the greatest games of all time, if not THE greatest. Vampire: The Masquerade - Bloodlines is the closest game I have ever played to the original Deus Ex. Awesome story, awesome gameplay, awesome everything really. It doesn't really get much love but everyone I know that has played it, has loved it.

@MordeaniisChaos: So you're saying just because there's a sequel coming people should ignore the previous ones? Yeah that totally makes sense, I mean, when have the earlier installments of a game ever been better than the later ones? It's always "newer is better" deal. Right. Besides I'm not going to recommend games that have not even been released (you also recommended Arma 2 so I fail to see what you're raving about). I know Arma 2 is good, I know it's out and I know people should play it if they think it's something they'd like. I added Operation Flashpoint because I know some people like that more and I can understand why. By the way, Arma is the franchise name and not the first Arma game which was Arma: Armed assault or Arma: Combat Operations in NA.

He asked for very unspecific recommendations (no time frame, genre, pointers to what he likes, examples, nothing) and I gave him some and now you're telling me my advice on this very subjective matter is not good enough? Get a load of your bullshit! I'm sure if he doesn't want to follow my advice he just doesn't.

Half-Life 1 and 2, Crysis+Warhead, any Command and Conquer title released before the 3rd one (although that one isn't bad), Diablo 2, Max Payne and Battlefield 1942+expansions, just to name a few.

• Grim Fandango
• Command & Conquer: The First Decade
• Doom 3
• System Shock 2
• Max Payne
• Wolfenstein
• Fallout 3
• Day of The Tentacle
• American McGee's Alice
• Call of Cthulhu: Dark Corners of The Earth
• Dungeon Keeper 2
• Jones In The Fast Lane
• Commandos: Behind Enemy Lines

@Sticky_Pennies said:

• Planescape: Torment
• Quake III Arena
• Dragon Age: Origins
• Half-Life 1 & 2
• Diablo 2
• Deus Ex
• System Shock 2
• Starcraft: Brood War & Starcraft II
• Warcraft III & Frozen Throne (screw that WoW noise.)
• Duke Nukem 3D
• Mechwarrior 2
• Pool of Radiance
• Day of the Tentacle

You need to know your roots.

Edit: Linkified.

this and I would add baldurs gate 2, Thief series and star wars knights of the old republic.

Theme Hospital 
Tie Fighter 
Wing Commander 4  
MechWarrior/Mech Commander 
Company of Heroes
Homeworld Cayaclysm 
Battlefield 3 
GTA 4 Carmageddon mod 
Red Alert 2
Starlancer 
World In Conflict  
Check indie websites as there are too many to list

• Max Payne 2
• Fear 1 (The a.i is still ridiculously good, nothing really touches it still imo)
• Fear 2
• Deus Ex
• Civ 5

Theme Hospital

I'd pick up any games with an active modding community