Metal Gear Solid

Baldur's Gate 2
NPCs, dialogue and romances have not been bested.
GOG, why isn't this game here yet? QQ
Please tell me you're negotiating!

i don't have one fanboy game but there are some titles that helps me to take out some part of my life :)
Amiga:
-Centurion
-Syndicate
PC:
-Max Payne
-VAMPIRE THE MASQUERADE: REDEMPTION (whole medieval part, music @ Vienna hub)
-Doom and Doom2
-GABRIEL KNIGHT SERIES
PS2:
-Need for speed hot pursuit 2
DC:
-SHENMUE [!!]
GC:
-RESIDENT EVIL REMAKE
-RE4
-ETERNAL DARKNESS
X360:
-ASSASIN's CREED
-G.R.A.W. [both of them]
-Oblivion

Monkey Island without a doubt. The first 3 games, with 2 and 3 being the best. I just love the story, graphics, music, humour and characters like I love no other game :)

I am with Daedolon: System Shock draw me in so much that, at a point, I was actually screaming at the monitor (Six... Five.... Four... Three... Two.... No. Noo! NOOOOOO!!!!!!!). It is the only fictional material that ever made me do that. Heck, I probably screamed at only 4 or 5 real people in my whole life!

So hard to decide.
Ultima online back in its hay day, from 98-2001'ish (until they added trammel).
Myth II: Soulblighter, my favorite rts game of all time, nice epic single player but the main thing I remember was the multiplayer. It was the "half life" of rts games in it's day, tons of mods/conversions, good active community with events from time to time (tournaments, cups, etc).
Severance - The de facto "best" melee combat game imo, no game has came close to the great combat system in Severance, and it looks like there's nothing on the horizion close to it either.

Actually I am rather fond of Operation Flashpoint. I saw it in the shop the other day and was raving about....that said fanboyness just isn't in my nature. Also a big Deus Ex/SS 2 fan and for the cult favourite has to be the Close Combat series especially number 2!!! loved that stuff

Dungeon Crawl, aka Linley Henzell's Dungeon Crawl, aka Dungeon Crawl Stone Soup. No other game has held my interest for anything near the length of time that it has, and I would struggle to name another game that was in the same league as it in terms of design quality.

I can't believe nobody has mentioned Grim Fandango! Without any doubt (in my mind) the greatest game ever made... I would love a remix version - same game with re-rendered (or not pre-rendered) graphics which would look fantastic at modern resolutions - like they did with RealMyst or something....

I wasn't going to post in this thread, but here I go:
Tetris Attack.

I loved how it changed from a Platformer to a Shmup and back again. The level where you had to jump when the wind was blowing up the chamber was my favourite; though perhaps its because I did that level on my 12th birthday and everything else about that day seemed special (please blow chunks at will - rose tinted spectacles much).

So you might be able to guess from my username (also my steam name if you play tf2 any) that my favorite series by far is Castlevania. I have almost every game in one form or another, and still love to hook up the NES to get in some old school vampire slaying :P I've spent so many moments from my childhood on this awesome series... ahh the memories.
I'm still waiting for a 1080p hi def ultra detailed 2D (NOT 2.5D) version of a new Castlevania game...it would be so sweet but it'll probably never happen :(

The Metroid franchise, for me.

Jazz Jackrabbit 2
Best. Platformer. Ever.
VOTE FOR IT
And Unreal Tournament GOTY. Brought me into the PC game world. I hope I can play it on my deathbed.