1) Halo CE
2) Splinter Cell
3) Burnout Revenge
4) Left 4 Dead
5) GTAIV

In no specific order

Call of Duty 4: Modern Warfare
Grand Theft Auto IV
Gears of War 2
Aion: The Tower of Eternity
FF X

I cant give the games an order because they are on the same level ( I could easily put 20 games on the list they are all equal to me)

Secret of Evermore/Mana FF7/10/12 Diablo 1/2 Sim City 1 Resident Evil 1 2 4. Zelda WW/TP
Bioshock, Silent Hill 1 2 3 5, WipeOut 2079/HD, GT, Super Mario World/ Land 1-2, Shen Mue and many more.

Sorry for chosing more games but I cant put just 5 games on the list because I love them all. (In fact I could name atleast 10 games more).

1. Super Mario Bros. 3
2. Legend of Zelda Ocarina of Time
3. Super Mario 64
4. Resident Evil 4
5. Chrono Trigger

It'll be hard a new game to break down to wall of my all time Top 5. I could give a decent 6-20 any time though.

Tetris, tomb raider 2 ( ps1 ), god of war 2 ( ps2 ), nomad soul ( dreamcast ), metal gear solid 3 ( ps2 ). 

( no particulary order )

1-Desperados Wanted Dead or Alive(PC)
2-Diablo 2(PC)
3-Warcraft 3(PC)
4-Tenchu 2(PS1)
5-Mass Effect(360)

Starcraft
Metal Gear solid
Xenogears
Silent hill 2
Shadow hearts

goldeneye

loz oot

banjo kazooie

resident evil 4

yoshi's island

Chrono Trigger
The Legend of Zelda Ocarnia of Time
Maniac Mansion
Final Fantasy 6/9 tie
Super Mario world 2

Super Mario Brothers (NES)
God of War (PSP)
Final Fantasy VII (Now on PSN)
Gears of War (360)
Pole Position (Commodore 64)