My Favourite Game Series is Quake.

PC

Call Of Duty 4
Wolfenstien 3D
Tony Hawks Pro Skater 2
Quake III Arena
Doom 2
Age of Empires 2: Age Of Kings
Sim Theme Park
Quake 4

Xbox 360

Project Gotham Racing 3
Project Gotham Racing 4
NBA 2k6
Halo 3
Halo 3: ODST
Halo Reach
Mass Effect
Mass Effect 2
Mass Effect 3
Crackdown
Crackdown 2
Colin Mcrae: DiRT
Call Of Duty 3
Call Of Duty: Modern Warfare
Call Of Duty: WaW
Call Of Duty: Modern Warfare 2
Call Of Duty Black Ops
Call of Duty: Modern Warfare 3
Call Of Duty: Black Ops 2
Perfect Dark Zero
Battlefield: Bad Company 2
Rainbow Six Vegas
Rainbow Six Vegas 2
Medal Of Honor Airborne
Elder Scrolls: Oblivion
Skyrim
Fable 2
Far Cry 2
Harry Potter: ootp
Red Faction: Guerilla
Splinter Cell: Conviction
Brothers in Arms: Hells Highway
Lego Harry Potter: Years 1 - 4

PS2

Smackdown Vs Raw 2006
Black

GBA

Pokemon Red
Pokemon Blue
Pokemon Ruby

PSP

Syphon Filter: Dark Mirror
Call Of Duty: Roads To Victory
Sonic Rivals

Absolute favourite is Mass Effect 2.

Other highlights included
Single Player: Syphon Filter: Dark Mirror, Oblivion, Medal of Honor Airborne.
Multiplayer: Age of Empires 2, Quake 3, Rainbow Six Vegas 2.

Worst games I have completed
Crackdown 2 (it felt like a chore)