After teasing players for a few days, Valve has “announced”:http://www.steampowered.com/index.php?area=news&id=364 the availability of a Deathmatch add-on for Half-Life 2. It is only available via Steam, so of course all of the servers are completely slammed at the moment. The download features 2 levels, and all players start with a gravity gun, pistol, SMG, and grenades, and you can pick up the rest of the weapons throughout the levels.

Valve also released the Half-Life 2 SDK, to help all of the inevitable mods get under way.

There is also a level design contest, where the winner will take home $5,000, along with 2 runner-up prizes of $3,000.