1. Unreal Engine 3 by Epic Games

games that used it: Unreal Tournament 3, Bioshock 1 & soon 2, Gears of War 1&2, Tom Clancy’s Endwar, Mirror’s Edge, X-men Origins Wolverine, Section 8 , Mass Effect 1&2etc …

2. Unreal Engine 2 by Epic Games

games that used it: Unreal Tournament 2003/2004, Unreal 2 The Awakening, Splinter Cell, Splinter Cell Double Agent/Pandora Tomorrow/Chaos Theory, Men of Valor, Brother in Arms – Road to Hill 30, Postal 2, America’s Army, Lineage 2 etc…

3. Source by Valve

games that used it: Half Life 2 + Ep1&2, VtM – Bloodlines, Team Fortress 2, Portal, Counter Strike Source, Left 4 Dead 1&2 etc

4. id Tech 3 by id Software

games that used it: Quake 3, the first ever Call of Duty, Star Wars Jedi Academy/Jedi Knight Outcast II and Medal of Honor Allied Assault + the two expansion packs (Spearhead and Breakthrough), Return to the Castle Wolfenstein, etc

5. Aurora by Bioware

games that used it: Neverwinter Nights 2 (updated version called Electron Engine), Knights of the Old Republic 1&2, The Witcher, Neverwinter Nights + Expansions etc…