Microsoft just showed off Crackdown 2 and Left 4 Dead 2 at its E3 conference and said both were exclusive to Xbox 360.

Crackdown 2 is due out in 2010 from Ruffian Games, as rumoured, and seems to have a multiplayer focus according to Microsoft's announcement release. Left 4 Dead 2 is due out on 17th November this year, and Valve subsequently said it was coming to PC at the same time.

The game "adds melee combat to enable deeper co-operative gameplay, with items such as a chainsaw, frying pan, axe, baseball bat, and more".

The AI director has been updated to procedurally change weather effects, world objects and pathways in addition to the usual stuff. Expect new survivors, zombies, bosses and campaigns.

Ubisoft then showed off Splinter Cell: Conviction, with a lot of fancy CG footage and Sam Fisher smacking people around. It will be released "this fall exclusively on Xbox 360".

Prior to that, Epic unveiled an Xbox Live Arcade exclusive called Shadow Complex, developed by Chair Entertainment.

Shown off by Chairs Donald Mustard and Epics Cliff Bleszinski at the Microsoft E3 conference, its a 2D side-scrolling action game with exploration punctuated by moments of combat, in which you play as a chap called Jason Fleming, collecting power-ups and upgrading your character. It's based on the world of Orson Scott Card's novel Empire.

Poor old Mustards microphone didnt work initially, but Cliff Bleszinski distracted us with a t-shirt that had Bill Gates mug-shot on it.

Big Park then showed a new XBLA game called Joy Ride, which is due out this winter and uses Avatars. Its a free download too, and lets you share racetracks. The announcement release suggests that you will be able to buy extras like new tracks, game modes and avatar items.

Check out our live coverage of the Microsoft conference for more, including Ellie's description of the on-stage Conviction demo.