Zombie Panic! Source

'Zombie Panic! Source' is a multiplayer Half-Life 2 first-person shooter modification that pays homage to the popular Zombie genre of film and games. It is the sequel to the Half-Life modification Zombie Panic!, which is available to download for free.

Gameplay
The game features four modes of gameplay, Zombie Panic! Survival mode, Zombie Panic! Objective mode, Zombie Panic! Hardcore mode, and ZPA mode. In survival mode, the zombies start with a number of lives based on the amount of players which are slowly depleted as zombies are killed and subsequently come back. In this mode, the round can only be won if one side completely destroys the other or after 15 minutes and survivors are still left standing. A Zombie life is gained if a human is killed and the human that dies, respawns on the zombie team. Objective mode introduces a set of objectives the survivors must complete. The zombie team has an infinite number of lives in objective mode, so zombies can always join the action again if they are killed. Hardcore mode dramatically increases the strength of the undead horde. Survivors must survive for 5 minutes rather that 15, but this shorter time to beat is compensated by more zombies at the start, all of these initial zombies are capable of infection (75% chance when hitting a survivor) and firearms and explosives do less damage. ZPA mode (The acronym for the "A" has never officially been revealed) includes infinite respawns for both the humans and zombies (survivors in waves of 20 seconds), a main objective (usually hold a control point for a certain amount of time) and side objectives (winnable by both teams, gives more carriers for zombies, more weapons for humans). The teams are also autobalanced. This mode was created to offer a more competitive mode to ZPS.

Scattered throughout the levels are various forms of furniture, decor, and miscellaneous items that can be used to block zombies and/or barricade a room or location of choice. Also available is a dedicated barricading-tool; the hammer, which can be used to nail boards to walls.

Humans
Humans start with a handgun and a melee weapon. Survivors have access to a wide variety of firearms and melee weapons alike to aid them in fighting off the zombie team, but they must be obtained first as they are scattered across the map.

Zombies
They start in small numbers, with the goal of thwarting the humans' attempts at survival or completion of objectives. Zombies have an alternative vision mode which brightens any light sources present and causes survivors to appear with a red aura, and green for infected survivors.

Carrier
The Carrier zombie is a pale, slightly stronger zombie that carries a set (10% default) chance of infection when attacking a survivor. There is only one carrier each round, however more are present in some game modes (e.g., hardcore mode, ZPA ). If a human is infected, they will eventually turn into a zombie. When infected, the survivor becomes vulnerable to friendly fire, allowing other survivors to kill them before they turn. These humans change from the normal red to green in the perspective of attacking zombies using zombie vision. In ZPA, to replace infection, there is wounding, where damage is caused to the survivor over a period of time.

Weight
Weapons and ammunition both slow the player down. This forces the player to ration their inventory, unlike most first-person shooter games.

History
''Zombie Panic! Source'' began development in early 2005, and released their first public beta on December 28, 2007.

In 2006, ''Zombie Panic! Source'' was picked as one of ModDB's top 100 unreleased mods of the year.

In 2007, ''Zombie Panic! Source'' won ModDB's player's choice unreleased mod of the year.

On February 9, 2008, ''Zombie Panic! Source'' was discussed in the first ModDB podcast.

The mod was also featured in the March 2008 issue of PC Gamer, UK Edition.

On October 8, 2008, it was one of the first five "mods" to be released on Steam by Valve under their new commitment to easily accessible quality user-created modifications in the Steam Store.

On October 29, 2009, ''Zombie Panic! v2.0'' was released earlier rather on October 31, 2009. Existing players received an automatic update.