Best PC games ever played?

Mass effect 1, Assassins creed 2, Bioshock Infinite, GTA san andreas

DE:HR, Amalur, Alan Wake, Tomb Raider, maybe Infinite...

Baldur's Gate II: Shadows of Amn

Bastion - the most strong story, art, music and emotions for me. I really recommend playing it if you haven't done it before.

Battlefield 3 - MW3 MW2 - CIV5

Black & White, Half-Life series, Portal series, Bioshock series (yes, all of it), in more recent times- Giana Sisters: Twisted Dreams.

I have played a shitload of PC games and one that has kept me occupied the most is World of Warcraft so that has to mean something.

Tomb Raider.Almost all of them.But the recent one gave me a great feeling of accomplishment after I finished it.

Quake

Warcraft 3 + Addon, all Bioshock Titles, old C&C games.

So many, i'll limit my answers to the first ones that come to mind, Morrowind, KOTOR and To the Moon.

edit: sorry, u said PC

Can't boil it down to just one, so here goes:
-Planescape Torment
-Majesty: The Fantasy Kingdom Sim
-Ultima 7
-Europa Universalis 4
-System Shock 2
-Thief: The Dark Project
-Fallout 2
-Riven
-Vampire the Masquerade: Bloodlines
-Rainbow Six 3: Raven Shield
-Age of Wonders 1

These are the first that spring to mind

GTA: Vice City, GTA: San Andreas, Mafia: City of Lost Heaven, TES III: Morrowind, The Binding of Isaac, Hotline Miami

There are too many to name :)

• the first Assassin's Creed
• Thief (TDP, Metal Age and Deadly Shadows)
• Dishonored
• the first L4D
• Terraria
• Dark Fall: Lost Souls
• Vampire the Masquerade: Redemption
• Plants vs. Zombies
• World of Warcraft (especially the Burning Crusade)
  ... and many more

Max Payne 1 and 2
HoMM 3
Quake III Arena
Commandos: Behind Enemy Lines
Mount & Blade Warband
Half-Life
Doom II
Dark Messiah of Might and Magic
Diablo II

Borderlands 1.

Mafia 2: nothing can ever beat that game... So many feeling, great story and everything was just done right. Except the face animations, but in the end it didn't really matter. ^^
The Walking Dead (just played first season): Also good feelings because of those interactions between characters or kinda like defending "your" child.
Bioshock Infinite as the thread opener already noticed: Such a nice environment, great story...
Metro 2033 and Last Ligh: Both are really awesome, great feeling playing it and I like the "environment".

Worms
Diablo
Road Rash
Need for Speed
Carmageddon
Blade Runner
Heroes 2 & 3
Baldur's Gate...

Diablo II
Titan Quest
Heroes of Might and Magic III
Borderlands
The Witcher

Sleeping Dogs
Alice Madness Returns
Batman Arkham City
F.E.A.R
Dead Rising 2
Bioshock 2
Remember Me
Mafia II
Dead Island
Wolfenstein: The New Order
Cognition: An Erica Reed Thriller

Any game with a great storyline. I really enjoy to play these games as I watch a movie.

Dark Souls.

armadillo run. :)

Microsoft Minesweeper

りゅがごとく and nothing simulator 2015.must OWN

System Shock & System Shock II - I still play these occasionally. I know Citadel Station like the back of my hand.

Mechwarrior 4 - at the hight of our after-work gaming sesisons. Order pizza in and blow away coworkers. Playing with CH Combatstick, Pro Throttle and Pedals. :D

Descent - With Flightstick and Pedals, this was amazing. I remember multiplayer being amazing too, except that it was asynchronous, meaning that my 368 updated slower than the 468's and they could literally fly rings around me! :(

Alone in the Dark - the first one. Very Lovecraftian and cinematic.

DOOM - Have bought this for more systems than any other that I'm aware of: PC (several times), 32x, GBA (4 copies) and iOS. Another game I know like the back of my hand - when my brother got it for his SNES, he had me direct him and it was all "turn here, push this spot, etc." This was years after I played through it on the PC (I got the 32x version cheap used some time later) and I was a little surprised myself.

Ultima IV - The series got more refined than this, but the gameplay, music and MORALS really brought things together in this game. It's still my favorite Ultima game, and I've played throuh it 4-5 times (some of those were on my C64!)