Your Top 20. RULES, MOFOS. CLOSED.

[Yoru]

Unordered, but pedantically sorted in chronological order.

Monkey Island 2: LeChuck's Revenge - LucasArts - PC - 1991
SimCity 2000 - Maxis - PC - 1993
Sid Meier's Colonization - Microprose - PC - 1994
Alan Lenton's Federation - IBGames - PC - 1995 (MUD, originally on Compunet in 1988, date listed is the worldwide AOL debut)
Civilization II - Microprose - PC - 1996
Master of Orion 2 - Microprose - PC - 1996
Team Fortress - Team Fortress Software - PC - 1996 (Mod for Quake/Quakeworld)
Fallout 2 - Black Isle Studios - PC - 1998
Sid Meier's Alpha Centauri - Firaxis - PC - 1999
Planescape: Torment - Black Isle Studios - PC - 1999
Homeworld - Relic Entertainment - PC - 1999
The Sims - Maxis - PC - 2000
Deus Ex - ION Storm - PC - 2000
Giants: Citizen Kabuto - Planet Moon - PC - 2000
Sacrifice - Shiny - PC - 2000
Europa 1400: The Guild - D4HEAD Studios - PC - 2002
EVE Online - CCP Games - PC - 2003
Phoenix Wright: Ace Attorney - Capcom - DS - 2005 (Originally GBA, 2001, but the rerelease is better)
The Elder Scrolls 4: Oblivion - Bethesda Softworks - PC - 2006
Portal - Valve Software - PC - 2007

[Tebonas]

Only 20? Thats too hard, I'll have to stick to the bare essentials:

Sundog: Frozen Legacy - FTL Games - Atari ST - 1984
Ultima 4 - Origin - PC - 1985  (Ultima Underworld would be the contender, only one in a series allowed)
Tetris - Spectrum Holobyte - PC - 1986
Nethack - DevTeam - PC - 1987 (honorary mention Rogue by Epyx and Adom. Only 20, sorry folks)
Pirates - Microprose - PC - 1987
The Lurking Horror - Infocom - PC - 1997 (for all those text adventures i devoured back in the day, I had to say one name)
Pool of Radiance - SSI - PC - 1988 (first of the gold box games, Baldurs Gate, I'm your father)
Wasteland - Interplay - PC - 1988 (sorry Fallout, mind your elders)
Kick Off - Dino Dini - Atari ST - 1989 (the sports game I played in those days. Note the singular)
Sim City - Maxis - PC - 1989 (it was that or Populous, this has the staying power over the years)
Warlords - SSG - PC - 1990
Darklands - MicroProse - PC - 1992
Wing Commander - Origin - PC - 1992 (I should have chosen Elite over this, but I just can't. Its too dear to me)
Master of Orion 2 - Microprose - PC - 1996 (Master of Magic lost by a hair)
Planescape Torment - Black Isle Studios - PC - 1999
System Shock 2 - Looking Glass - PC - 1999
Deus Ex - Ion Storm - PC - 2000
Civilization 4 (Fall From Heaven) - Firaxis - PC - 2005
Mass Effect - Bioware - PC - 2007 (if its only 20 games, the Kotors lose to this)
Portal - Valve - PC - 2007

[Modern Angel]

I'm bad at remembering dev names and years so I'm just posting. No particular order. EDIT: So I remember more dev names than I thought. Don't recall years.

1. World of Warcraft - Blizzard - PC -2004
2. Team Fortress 2 - Valve - PC -2007
3. The Elder Scrolls: Morrowind - Bethesda - PC - 2002
4. The Legend of Zelda: A Link to the Past - Nintendo - SNES - 1991
5. Europa Universalis II - Paradox - PC - 2001
6. Crusader Kings - Paradox - PC - 2004
7. Civilization 4 - Firaxis - PC - 2005
8. Sid Meiers Pirates! (the remake) - Firaxis - PC - 2004
9. Portal - Valve - PC - 2007
10. Battlefield 1942 and expansions - PC - 2002
11. Guild Wars (Yeah, I know. For one brief, shining moment at release it was amazing for me and my real life friends) - NCSoft - PC - 2005
12. General Chaos - Genesis - 1994
13. Victoria Revolutions (I'm a Paradox fan, what can I say?) - Paradox - PC - 2006
14. Combat Mission: Barbarossa to berlin - Battlefront - PC - 2002
15. Planescape Torment - Black Isle - PC - 1999
16. Baldur's Gate 2 - Bioware - PC - 2000
17. Alpha Centauri - Firaxis - PC - 1999
18. Master of Magic - Microprose - PC - 1994
19. Unreal Tournament - Epic - PC - 1999
20. Sega Genesis Shadowrun - Sega - Genesis - 1994

[Nevermore]

Chronological order.

Game	Company	System	Year
Maniac Mansion	Lucasfilm Games	Amiga	1987
MechCommander	FASA Interactive	PC	1998
Final Fantasy VII	Square	Playstation	1997
Final Fantasy Tactics	Square	Playstation	1997
Baldur's Gate	BioWare	PC	1998
Fallout 2	Black Isle Studios	PC	1998
Alpha Centauri	Firaxis Games	PC	1999
Planescape: Torment	Black Isle Studios	PC	1999
Soul Calibur	Namco	Dreamcast	1999
Suikoden II	Konami	Playstation	1999
Parasite Eve II	Square	Playstation	2000
Skies of Arcadia	Sega	Dreamcast	2000
Vagrant Story	Square	Playstation	2000
Phantasy Star Online	Sega	Dreamcast	2001
Dark Age of Camelot	Mythic Entertainment	PC	2001
Star Wars: Knights of the Old Republic	BioWare	PC	2003
City of Heroes	Cryptic Studios	PC	2004
Vampire the Masquerade: Bloodlines	Troika	PC	2004
Civilization 4	Firaxis Games	PC	2005
Mass Effect	Bioware	X360	2007

[losgar]

Title	Company	System	NA Release
Wheel of Time	Legend	PC	1999
Tecmo Super Bowl	Tecmo	NES	1991
Military Madness	HudsonSoft	TurboGrafix	1989
Twisted Metal 2	SingleTrac	Playstation	1996
Dune 2	Westwood	Genesis	1993
Baldur's Gate 2	BioWare	PC	2000
Super Bomberman	Sony	SNES	1993
Archon	FreeFall Associates	C64	1983
Shadowrun	BlueSky Software	Genesis	1994
Nobungas Ambition	KOEI	NES	1993
Pool of Radiance	SSI	Mac	1988
X-Com Ufo Defense	Microprose	Playstation	1995
Bubble Bobble	Taito	NES	1987
Ultima Online (Until Trammel)	Origin Systems	PC	1997
Halo	Bungie	Xbox	2001
AoE:The Conquerers	Ensemble Studios	PC	2000
Mortal Kombat	Midway	Arcade	1992
Shadowrun	BlueSky	Genesis	1994
FarCry	Ubisoft	PC	2004
Deus Ex	Ion Storm	PC	2000

[Tale]

Elite - David Braben and Ian Bell - C64 - 1985
Lords of Midnight - Mike Singleton - C64 - 1985
Paradroid - Andrew Braybrook - C64 - 1985
Kick Off 2 - Dino Dini/Anco - Amiga - 1990
Ultima Underworld: The Stygian Abyss - Blue Sky - PC - 1992
Mechwarrior 2 - Activision - PC - 1995
Descent - Parallax - PC - 1995
Wave Race 64 - Nintendo EAD - N64 - 1996
Fallout - Black Isle - PC - 1997
Unreal - Epic Games/Digital Extremes - PC - 1998
Starsiege: Tribes - Dynamix - PC - 1998
EverQuest - Verant - PC - 1999
Freespace 2 - Volition - PC - 1999
Combat Mission: Beyond Overlord - Battlefront - PC - 2000
Halo - Bungie - Xbox - 2001
Ghost Recon - Red Storm - PC - 2001
Star Wars: Galaxies - Sony Online Entertainment - PC - 2003
Star Wars: Knights of the Old Republic - BioWare - PC - 2003
Mount & Blade - TaleWorlds - PC - 2005
Battlefield 2 - DICE - PC - 2005


Notes
I'm thinking of SWG as pre-CU.
Mount & Blade is still described as being in beta, but has been for sale as a full game since 2005.
Near misses: Airborne Ranger (C64), F-19 Stealth Fighter (C64), Silent Hunter 3 or 4 (PC), Portal, the SSX series and World of Warcraft (long love-hate relationship).

(edit - fixing missed platform in one of my picks)

[Evildrider]

Ok, I'm more of a casual gamer.. I don't really play every single game that comes out.. or anything even near that.  However, I do have some games that managed to consume a crapload of time for me in the past.  Some of the old ones I put there for nostalgia and the fun I had with them at the time they came out.

Pyro 2 - Mike O'Brien - 1990 - old DOS game where you were a terrorist burning down government buildings.
Tradewars 2000 - Gary martin - 1988ish - Old game on BBS servers
Pools of Radiance - Strategic Simulations, Inc. - 1998 - MS-DOS
Wizardry - Sir-Tech Software, inc. - 1981 - Commodore 64
Doom - ID Software - 1993 - PC
XCOM: UFO Defense - MicroProse - 1998 - PC
Jedi Knight 2: Jedi Outcast - Lucasarts - 2002- PC
Baldurs Gate 2 - Bioware - 2000 - PC
Mortal Kombat 2 - Midway - 1993 - various (prefer Arcade Version)
Street Fighter 2 - Capcom - 1991 - various (prefer Arcade Version)
Killer Instinct - Rareware - 1994 - various (prefer Arcade Version)
Master of Orion 2 - Microprose - 1996 - PC
Starcraft - Blizzard - 1998 - PC
Mechwarrior 3 - MicroProse - 1999 - PC
Soldier of Fortune - Raven - 2000 - PC
Vampire the Masquerade: Bloodlines - Troika - 2004 - PC
Star Wars Galaxies - SOE - 2003 - PC - I know, I know.. this was my first ever real play at an MMO and it was an absolute blast for me, until it started to crash and burn. 
Dungeons and Dragons Online: Stormreach - Turbine - 2006 - Has it's flaws but is the only other MMO to keep my interest since I left SWG.
Gears of War - Epic Games - 2007 - PC Version
Marvel Ultimate Alliance - Raven - 2006 - various

[Prospero]

1) Quest for Glory 4 - PC
2) Tie Fighter - PC
3) Addam's Family Pinball Table - Arcade
4) Team Fortress 2 - PC
5) Half-Life - PC
6) Portal - PC
7) Starcraft - PC
8 )Gabriel Knight: Sins of the Father - PC
9) Psychonauts - PC
10) Mario Kart: DS - DS
11) Counter-strike:Source- PC
12) Puzzle Pirates - PC
13) Super Mario Brothers 3 - Nintendo
14) X-Com - PC
15) Guitar Hero 2 - XBox
16) Myth: The Fallen Lords - PC
17) Vampire the Masquerade: Bloodlines - PC
18) Pools of Radiance - PC
19) Alien Hominid - Gamecube
20) Natural Selection - PC

[Kludge]

It gets kinda geeky... Bear with me.

1.  Dominions III                                  Illwinter Game Designs           PC   2006
2.  Empire Earth II                               Vivendi Games                       PC   2005
3.  Final Fantasy VII                             Squaresoft                            PS1 1997
4.  Everquest II                                   Sony Online Entertainment    PC   2003
5.  Bioshock                                       2K Games (Boston??)             PC   2007
6.  Warcraft III                                    Blizzard Entertainment           PC   2003
7.  Metal Gear Solid 2: Sons of Liberty Konami                                 PS2  2001
8.  World of Warcraft                         Blizzard                                  PC   2004
9.  Everquest                                     Verant                                    PC  1997
10. Civilization IV                                Firaxis                                     PC  2005
11. World in Conflict                          Massive                                   PC  2007
12. Elder Scrolls IV: Oblivion              Bethesda                                 PC  2006
13. Supreme Commander                Gas Powered Games                 PC  2007
14. X-COM: UFO Defense                  Micropose                                PC  1993
15. Rollercoaster Tycoon                  Hasbro                                     PC  1999
16. Rome: Total War                       Creative Assembly                     PC  2004
17. Wall Street Raider                      Ronin Software                          PC  199x
18. Sim City 2000                            Maxis                                         PC  2000?
19. Diablo II                                     Blizzard                                      PC  2000
20. The General                               New Game Software                  PC  200x
[Ego killer...]

[schild]

Edit that shit down! Fucking directions! Read them!

[schild]

Super Mario Bros. - Nintendo Co., Ltd. - NES - 1985
Solomon's Key - Tecmo, Ltd. - NES - 1987
Castlevania 3: Dracula's Curse - Konami Industry Co. Ltd. - NES - 1989
Mighty Bomb Jack - Tecmo, Ltd. - NES - 1987
The Magic of Scheherazade - Culture Brain Inc. - NES - 1989
Super Metroid - Nintendo of Europe GmbH - SNES - 1994
Final Fantasy VI - Square Co., Ltd. - SNES - 1994
Shin Megami Tensei: Digital Devil Saga - PS2 - Atlus - 2005
Chakan - SEGA Corporation - GEN - 1992
Cannon Fodder - Sensible Software - JAG - 1995
Torneko: The Last Hope - Chunsoft - PSX - 2000
Parasite Eve - Square Co., Ltd. - PSX - 1998
Rogue Galaxy - Level 5 - PS2 - 2007
Guitar Hero 2 - Harmonix - PS2 - 2006
Planescape: Torment - Black Isle - WIN - 1999
The Typing of the Dead - Smilebit - WIN - 2000
Unreal Tournament - Epic - WIN - 1999
Deus Ex - Ion Storm - WIN - 2000
Shadow of the Colossus - Team Ico - PS2 - 2005
Fahrenheit - Quantic Dream - PS2 - 2005

[Phildo]

Chrono Trigger - Squaresoft - NES - 1995
Final Fantasy 4 - Squaresoft - NES - 1991
Knights of the Old Republic - Bioware - XBox - 2003
Red Alert 2 - Westwood - PC - 2000
Guitar Hero 2 - Harmonix - PS2 - 2006
Disgaea - Nippon Ichi - PS2 - 2003
Shadow Hearts: Covenant - Nautilus - PS2 - 2004
Final Fantasy Tactics - Squaresoft - PSX - 1998
Wild Arms - MediaVision - PSX - 1997
Shining Force 2 - Climax Entertainment - Genesis - 1994
Civilization - MicroProse - PC - 1990
Sim City 2000 - Maxis - PC - 1993
Langrisser 2 - NCS - Genesis 1994 (Japan)
TIE Fighter - LucasArts - PC - 1994
Actraiser - Quintet - SNES - 1991
Master of Orion 2 - SimTex - PC - 1996
Ratchet & Clank - Insomniac - PS2 - 2002
Katamari Damacy - Namco - PS2 - 2004
Sim Tower - OpenBook - PC - 1994
Where in the World is Carmen Sandiego - Broderbund - PC - 1985

Notes: Had to use the last one for Carmen Sandiego.  She deserves some love here.

Games I've never played include, but are not limited to: Planescapte: Torment, Vampire: Bloodlines, Fallout, Baldur's Gate, System Shock, Deus Ex, any MMO ever.

Doing this nearly cause my brain to implode.  There are so many games I had to leave off.  No sports games or FPS, and I'm ashamed of that.  Especially having to leave off things liks Tecmo Bowl or NHL 94/5/6.  Oh well, that's the list you're getting.  Deal with it.

[Nebu]

1.   Dark Age of Camelot - Mythic Entertainment - PC – 2001
2.   Battlefield 1942 - Electronic Arts - 2002
3.   Star Raiders – Atari - 1979
4.   A Tale in the Desert: Tale I - eGenesis – 2003
5.   Championship Manager – Sports Interactive - 1992
6.   Elite – Acornsoft - 1984
7.   Strat-o-matic baseball – Strat-o-matic – computer version 1990’s
8.   Civilization - MicroProse Software - PC – 1991
9.   M.U.L.E. - Ozark Softscape - C64 – 1983
10.   Legend of Zelda: A Link to the Past - Nintendo – SNES
11.   The Bard's Tale: Volume I - Interplay Productions - Atari ST – 1985
12.   Grim Fandango - Lucasarts - PC – 1998
13.   Oregon Trail (Broderbund? Apple IIe)
14.   Adventure - Atari - Atari 2600 – 1979
15.   Pitfall! - Activision - Atari 2600 – 1982
16.   Goldeneye 007 - Rare Ltd - N64 – 1997
17.   ReVolt – Acclaim - 1999
18.   Railroad Tycoon – Sid Meier - 1990
19.   Chuck Yeager Air Combat - 1991
20.   Jack Nicklaus Unlimited Golf & course design – Accolade - 1990

<many above are based more on nostalgia than on game quality>

[Rendakor]

Crystalis - SNK - NES - 1990
Rock n Roll Racing - Blizzard - SNES - 1993
Final Fantasy Tactics - Squaresoft - PSX - 1998
Final Fantasy VI - Squaresoft - SNES - 1994
Everquest 2 - SOE - PC - 2004
Base Wars - Ultra - NES - 1991
Portal - Valve - PC - 2007
Ogre Battle: March of the Black Queen - Quest - SNES - 1993
Pokemon Red - Game Freak - GB - 1998
Earthbound - Ape - SNES - 1995
Street Fighter Alpha 3 - Capcom - PSX - 1999
Super Smash Bros Melee - HAL Labs - GC - 2001
Bushido Blade 2 - Light Weight - PSX - 1998
Gauntlet Legends - Midway - Arcade - 1998
Secret of Evermore - Squaresoft - SNES - 1995
DDRMax2 7th Mix - Konami - Arcade - 2002
Resident Evil 2 - Capcom - PSX - 1997
Fallout 2 - Black Isle - PC - 1998
Super Mario RPG: Legend of the Seven Stars - Squaresoft - SNES - 1996
Starcraft - Blizzard - PC - 1998

In no particular order. After deciding which Final Fantasy to put on the list, the one game per series rule actually made this easier. However, its safe to assume that if a game is on my list I love the whole series (with the exception of every Final Fantasy after 9). The lack of early PC games is because I didnt own a computer at all for most of my youth, and didnt get one that could do more than play MUDs til '99 or so. SNES/PSX were my 2 favorite systems, and the games on here reflect that. Gauntlet Legends made the cut both because I dumped at least $20 in quarters into it to beat it one night, and because it was the first of the modern multiplayer action RPG genre (D&D Heroes, BG: Dark Alliance, FF:CC, etc) which I'm a huge fan of. Crystalis was my first RPG, so it always holds a place in my heart.

[Special J]

In no particular order:

1. Star Wars: TIE Fighter - LucasArts - 1994 - PC
2. Jedi Knight - LucasArts - 1997 - PC
3. Command & Conquer: Red Alert - Westwood - 1996 - PC
4. Master of Orion 2 - Microprose - 1996 - PC
5. Civilization 2 - Microprose - 1996 - PC
6. Soul Calibur II - Namco - 2003 - PS2
7. Baldur's Gate - Bioware - 1998 - PC
8. F-19 Stealth Fighter - Microprose - 1988 - PC
9. X-Com: UFO Defense - Microprose - 1993 - PC
10. Mechwarrior 4: Mercenaries - Microsoft - 2002 - PC
11. Street Fighter 2 - Capcom - 1991 - Arcade
12. Final Fantasy X - Square - 2001 - PS2
13. Doom - Id - 1993 - PC
14. Halo - Bungie - 2001 - XBox
15. Fallout - Black Isle - 1997 - PC
16. Diablo - Blizzard - 1996 - PC
17. Starcraft - Blizzard - 1998 - PC
18. Super Mario World - Nintendo - 1991 - SNES
19. Guitar Hero III - Activision - 2007 - 360
20. Wing Commander: Privateer - Origin - 1993 - PC

I know as soon as I post there will be something I'll kick myself for leaving out.  There are a few that were hard to cut off the list.  Heavy PC slant since that where most of my gaming used to be.

[Sauced]

Kid Icarus - Nintendo - NES - 1987
Knights of Legend - Todd Porter / Origin - C64 - 1989
Super Mario Bros. 3 - Nintendo - NES - 1990
Out of this World - Delphine Software - SNES - 1991
Legend of Zelda: A Link to the Past - Nintendo - SNES - 1992
Shadowrun - Beam Software - SNES - 1993
Final Fantasy VI - Square - SNES - 1994
The Elder Scrolls: Daggerfall - Bethesda - PC - 1996
Fallout - Black Isle - PC - 1997
Starcraft - Blizzard - PC - 1998
Planescape: Torment - Black Isle - PC - 1999
Vagrant Story - Square - PS1 - 2000
Ico - Team Ico - PS2 - 2001
Beyond Good & Evil - Ubisoft - PS2 - 2003
Shadow of the Colossus - Team Ico - PS2 - 2005
God of War - SCE - PS2 - 2005
Dragon Quest VIII - Square Enix - PS2 - 2005
Psychonauts - Double Fine - PS2 - 2005
Guitar Hero 2- Harmonix - PS2 - 2006
Portal - Valve - PC - 2007

Apparently 2005 was the greatest year ever.  Who knew?