Zombie Panic: Source is a multiplayer game and modification for Half-Life in which the human team must fend for themselves against a horde of zombies. It is currently available to all owners of Half-Life, and can be downloaded free of charge. The mod has a creepy feeling to it and is designed to imbue the player with a sense of desperation. Overall, fun and playability take preference over realism and horror. Release Date: 12/28/2007