Counter-Strike: Source is Valve's incredibly popular first-person-shooter which pits terrorists against counter-terrorists.

In deathmatch mode, players "respawn" seconds after they die, and continue to do so until the end of the session - professional gamers consider this the best way to improve aim and show off raw skill.

For more details of this game, head over to www.counter-strike.net

Left 4 Dead is Valve's most recent release, a multiplayer cooperative first-person-shooter with a zombie theme.

Critically aclaimed from the start, Left 4 Dead has received a number of awards including IGN's Best Multiplayer Game of 2008, and has sold millions of retail copies, as well as many more via Valve's online distribution software, Steam.

For more details of this game, head over to www.l4d.com