When Valve promises a surprise, they deliver. A new multiplayer deathmatch game based on the Half-Life 2 engine is available for download on Steam - if you have the game, go get it! Then there's the Half-Life 2/Source SDK, which means top mod-makers are already hard at work creating new worlds for you to explore. If you're one of them, there's a $5,000 prize for the top deathmatch map...
