This is really about PC and also console games (sorry for board game maniacs :) )

Mine fave' list is:

DeusEx 1
Half-Life 1
Half-Life2
Resident Evil 1
Stronghold and Stronghold:Crusader

Ookay, can we try and keep it to a minimum of top 5 favourite games... :P

...as to be honest, I can't think of more than 5 off the top of my head (maybe if I went to write them down) ::)

1. Prince of Persia - Warrior Within
2. Grandia Series (Grandia 3 best)
3. Final Fantasy Series (FFVII best)
4. Resident Evil Series (Resi. 4 best)
5. Unreal Tournament (original - not new ones)

Command & Conquer: Red Alert2:Yuri's Revenge with Purple Alert Mod.
Star-Wars: X-Wing Alliance with Xwingalliace upgrades installed.
Descent 1 through 3 all variants
Star-Wars: Episode I: Racer
Star-Wars: X-wing V.S. Tie Fighter
Star-Wars: X-wing V.S. Tie Fighter: Ballance Of Power
Star-Wars: Rogue Squadron 3D
Unreal Ver2.26
Unreal Tournament Game Of The Year Edition 1999
Flight Simulator 2004
QuakeIIIArena 1.32
Tactical Ops
Star-Wars: Dark Forces
Star-Wars: Dark Forces II: Jedi Knight
Star-Wars: Jedi Knight: Mysteries Of The Sith
Star-Wars: Jedi Knight : Jedi Outcast
Star-Wars: Jedi Knight : Jedi Academy
Call Of Duty
Call Of Duty: United Offensive
Call Of Duty 2


LoL forgot a  few haha :-X

Half Life
Command & Conquer Red Alert
Gran Turismo 4
CounterStrike 1.6
Command & Conquer Generals
Half Life²
You dont know jack
Unreal Turnament
Gran Turismo 2
Need 4 Speed 2se (@ Voodoo2 SLI)

Descent Patched for Glide
GLQuake
HalfLife
SOF
UNREAL
Undying

Operation Flashpoint
Half Life 2
Counter Strike Source
Day of Defeat Source
Unreal Tournament 2004
Flatout
Need for Speed Most Wanted

This was kind of hard cuz there has been alot of really good games, but I think my list are as follows.

Shadow Warrior
UT
Thief series (all three)
Baulders Gate/IWD series
NWN
Rainbow Six 3 *
Ghost Recon *
Delta Force Games *
(*although good games, these are on here more for the co-op multiplayer maps these offer instead of just death match stuff)
CoD and Medal of Honor series

DeusEx 1
Half-Life 1
System Shock 2
Quake I & II
Star Wars Dark Forces
Hioctane
F.E.A.R.
Thief I
SOF
Wheel of Time
Heretic I & II
Doom

Added:

No One Lives Forever 1 & 2
Call of Duty

Doom
Quake 1 & 2
Rayman 2
Soldier of Fortune 1 & 2
Half-Life 1 & 2
DeusEx 1
System Shock 2
Thief 1, 2 & 3
Wheel of Time
Undying
Unreal Tournament 99
No One Lives Forever 1 & 2
Medal of Honour
Call of Duty
F.E.A.R.

Really I don't know :-/
Some names that iI have in mind in this moment are Deus Ex , System Shock , Morrowind , Fallout , Thief , Might and Magic , Ultima Underworld and last but not the least Stonekeep...

well the games you entered do suit you right enough hay ;)

What also a great Mod for Unreal Tournament Game Of The Year Edition 1999 was named Operation To Na Pali, you can dwonload it here , not to worry it's a free made mod:
http://www.planetunreal.com/teamvortex/help/

my fave games are

Half-Life 1 & 2

Counter-strike all of them but 1.6 & CZ more

Quake III Arena ;D

Shenmue (on the Dreamcast) :D

Settlers 2 Gold Edition
Command & Conquer Red Alert
Transport Tycoon Deluxe
Imperium Galactica 2
Super Mario World (SNES)
Sim City (SNES)
Warhammer: Dark Omen
Need for Speed 3: Hot Pursuit
Theme Hospital
Command & Conquer Tiberian Sun

Final Fantasy VIII
Biohazard II & III
Gran Turismo 1,2,3,4
Hard Truck 2
Flight Simulator 2K
18 wheels across American,voyage
and  Parasite Eve 2, ;D

In order of apparence:

Terminal Velocity
C&C RA1
Blood
Carmageddon 2
Rollcage
C&C Tiberian Sun
Unreal Tournament
Soldier Of Fortune
DeusEx
Serious Sam