Valve has just published five ambitious Source Mods on their download/shop platform STEAM. The mods are free of charge for owners of any Source-based game like Half-Life 2, Team Fortress 2 or Portal. Also, they offer a special price this weekend for Half-Life Episode 1 (which is also source-based and stand-alone): 4,99 Dollars instead of 9,99. Update: The special price offer has ended.

The five mods are:

1. Age of Chivalry: A story-driven multiplayer game with several classes like footmen, archers and knights. Weapons include swords and bows, but also siege engines like catapults.

2. D.I.P.R.I.P.: "Die in Pain, Rest in Peace" is the lovely title for this armored car mayhem. Vehicles use multiple weapon mounts and fight in malls, refineries, country food storages or military bases.

3. Insurgency: Represents the modern battlefield on the individual and tactical levels. Only the best players will become commanders and get the chance to lead its entire team towards victory.

4. Zombie Panic Source: A cooperative survial-horror mod where you are one of a group of survivors. There are many ranged and melee weapons, the "Carrier zombie" which can turn friend into foe.

5. Synergy: The game is mainly focusing on cooperative play with Combine versus Rebel teams, but has several other modes. You fight through individual levels or campaigns, including Half-Life 2.

Once installed, the Mods will appear in the Steam "My Games" list. The Mods will receive automatic updates just like other games on Steam, and take advantage of "Steamworks", which is "providing stat tracking and tighter integration with the Steam community", according to Valve.