The ZM source code was released in June 2009 on the ZM forums. Now you can also get it here on ModDB. Be sure to check the included readme file.
Zombie Master In Short
Zombie Master is a multiplayer Half-Life 2 modification, centred around a zombie-apocalypse, which throws all but one player in the shoes of human survivors. Pitched against a relentless tide of rotting flesh, they must scavenge for weaponry and equipment just to stay alive. But that one player, chosen randomly at the beginning of the round, is not bound by mortal restraints.
To speak his name is to invite the wrath of hell - but most call him the 'Zombie Master'. He is nigh omnipotent. His invisible hand controls the legions of undead like puppets on strings; slowly closing the net on the humans while they run to and fro like rats in a maze.
* A wide range of weapons to scavenge such as shotguns, molotov cocktails, rifles and more
* A number of challenging objectives that encourage players to team up and work together
* The ability to interact with the environment to build barricades and carry objects
* Real Time Strategy gameplay; create and command your own undead horde
* A wide variation of zombie units encourages the ZM to adopt complex tactics
* Environmental "manipulates" allow the ZM to interact with the world in devilish ways
* Mysterious powers let the ZM manifest his power in a more direct fashion... for a price
Zombie Master 1.2.1 has been released, fixing many of the more pressing bugs present in version 1.2.0 and tweaking game balance.
Summary of the changes in 1.2.1:
The new version is only available as a full installer download. You do not need any previous versions of the mod installed. If you're new to ZM, do make sure you own a Steam game that includes the Source SDK Base. Most Valve games like HL2, TF2 and L4D do include this, so if you own one you are ready to play.
Zombie Master 1.1.2 to 1.1.3 Linux patch