Killing Floor is a cooperative survival horror first-person shooter developed and published by Tripwire for the PC (via Steam) on May 14, 2009.
Up to six players fight against waves of "Specimens", failed genetic super-soldiers (from the London-based Horzine Biotech corporation) with zombie-like properties. Along the way, they purchase deadlier weaponry from a roaming Trader and gain persistent experience for each of their character classes (known as Perks, which give the player unique benefits).
The game is based on a 2005 mod of the same name for Unreal Tournament 2004. With assistance from the game's original mod team, most of the game's concept and assets were translated over to the final retail version without many changes. Throughout the years, the game received free content packs (including annual special events) and paid DLC (including characters and weapons), including cross-promotions with other games (such as Tripwire's Red Orchestra 2: Heroes of Stalingrad and Valve's Portal 2).
The game was later released for the Mac (on May 5, 2010) and most Linux platforms (on November 10, 2012). A top-down spin-off, titled Killing Floor: Calamity, was released for the Ouya. The game will receive a full-blown sequel, titled Killing Floor 2, soon.
In Killing Floor, players team up with up to 5 other players to survive against waves of Specimens, or Zeds as they are more commonly known. Players must kill all Zeds in a wave, and after that, get a period of time to rest and rearm. They will fight through a set number of waves, culminating in a boss wave where players pit their wits against the game's boss, the Patriarch. Most of the maps are set in Great Britain, and the cast of characters all hail from the Isles, featuring many stereotypical accents and slang.
There are 5 levels of difficulty in Killing Floor: Beginner, Normal, Hard, Suicidal, and Hell on Earth. Each level, and the number players in the team, increases Zed hitpoints, damage, and number spawned per wave. There are also 3 game lengths, Short with 4 waves, Medium with 7 waves, and Long with 10 waves. Most servers run Long games.
After every wave, players get a chance to buy new weapons and equipment at the Trader. The Trader is spread out in specific spots in a map, and is open only during the rest period. Players must make their way to her within the rest time allocated, or they will have to fight the next wave with their current equipment and ammunition. She accepts British Pounds (£) as currency, which are rewarded to a player for killing Zeds and surviving a wave. Players can also trade cash with each other, which allows newcomers to get equipped with the necessary equipment to survive the next wave.
Players can heal themselves, and each other, with their equipped Medical Syringes. These syringes are available for every player, but is limited to the amount of charge they have. Each heal takes up 50 charge, but self-heals take up 100 charge, emptying the syringe. The charges will replenish over time, and the recharge rate is increased with the Field Medic perk.
Players can dictate the movement of Zeds by shutting off passageways and doors. They can also weld doors to slow down Zed movement, as they will now have to break down those doors before passing through. Welders are available to all players, and Support Specialists gain welding bonuses in their perk.
A special feature called "Zed Time" is triggered when players perform gory kills, such as headshots. Zed Time slows down time for all players, even in multiplayer, for a period of time. The Commando and Berserker perks can increase this bonus time by killing additional Zeds while in Zed Time.
Perks are upgradable player classes that each player chooses when they enter the game, granting them special bonuses tied to a particular playstyle (for example, Firebugs excel at fire-based weaponry while Field Medics excel at healing). In-between waves, players have the option to switch to another class (but only once per wave). By performing specific tasks (no matter what Perk they choose), players can gain experience and level up their Perks (to a maximum of six levels), providing additional bonuses.
The Field Medic specializes in healing injured players. Field Medics get buffs with the Syringe, Combat Armour, and Medic Guns. They also have higher movement speed, have resistance to Bloat bile, and have the ability to heal teammates with their grenade explosions. They gain Perk experience by the amount of healing done to their teammates.
The Support Specialist specializes in defensive tactics, gaining buffs with the welder, grenades, and shotguns. They are also less burdened with the weight of their inventories. They gain Perk experience by both the amount of damage dealt with shotguns and the amount of welding done. (Both are unique requirements and must be gained separately to level up)
The Sharpshooter specializes in both long-ranged weaponry and dealing heavy damage from accurate headshots, gaining buffs with all pistols and marksman weapons (such as standard rifles and crossbows). They can also deal better headshot damage from any other weapon. They gain Perk experience by the amount of decapitation kills from headshots.
The Commando specializes in reconaissance, as Commandos have the unique ability to specify the exact amount of health of each nearby enemy. They also gain buffs for both assault rifles and battle rifles, can detect cloaked enemies within a certain distance, (This includes both Stalkers and the Patriarch) can reload weaponry faster, and can extend the slow-motion Zed-Time. They gain Perk experience by both the amount of damage dealt with assault rifles or battle rifles and the number of Stalkers killed with assault rifles or battle rifles. (Both are unique requirements and must be gained separately to level up)
The Berserker specializes in close-ranged combat and damage resistance, gaining buffs with all melee weapons. They have damage resistance to all forms of damage (with bonus resistance to Bloat bile), can extend the slow-motion Zed-Time, and cannot be slowed down by being grabbed by a Clot. They gain Perk experience by the amount of damage dealt with melee weapons.
The Firebug specializes in mob control, gaining buffs with all incendiary weapons. Firebugs are also resistant to fire damage (usually dealt by themselves and Husks) and can ignite enemies by their grenade explosions. They gain Perk experience by the amount of fire damage dealt (to enemies) with incendiary weapons.
The Demolition specializes in dealing explosive damage, gaining buffs to grenades and all explosive weaponry. Demolition experts are also resistant to explosive damage (usually dealt by themselves and the Patriarch). They gain Perk experience by the amount of explosive damage dealt to enemies.
Commonly referred to as Zeds (or "zombies"), Specimens are failed clones of experimental super-soldiers created by the Horzine Biotech corporation and the main antagonists players will fight. There are ten types of Specimens in the game (including a special boss that is fought at the end of each match).
On special events (during Summer, Halloween, and Christmas), each Specimen receives a new appearance and new sounds to match. There are currently four themes:
As of December 2, 2014, servers can toggle between normal, Summer Sideshow, Hillbilly Horror, and Twisted Christmas themes for all Specimens.
The Clot is the most common Zed in Killing Floor. It does not have any special abilities, nor does it deal much damage, but it can grab players and keep them from moving. This allows more dangerous Zeds to approach distracted players.
Clots are clones of Kevin Clamely's deceased son, with genetic alterations to make it tougher than normal humans.
The Bloat has a lot of hitpoints, and spews corrosive vomit on players that stray too near to it. When killed, it will explode, spraying it's vomit around its corpse. The Bloat's vomit can affect surrounding Zeds, and good players can force it to spew vomit on tougher Zeds, transferring aggro to the Bloat.
The Gorefast, like its name suggests, is a fast moving Zed that wields a long blade grafted on it's left arm. It will chase down players that it sees and cut them open with its blade-arm. Groups of them can mean death for unprepared players.
The Stalker appears cloaked to players, and will only appear when attacking. It will, however, cast a shadow even when cloaked, which players can use to spot invisible stalkers. Commandos can also see Stalkers if they are close enough.
The Crawler is a spider-like creature that can appear in even the smallest cracks, and jump upon unsuspecting players. They like to operate in groups, and their small size and jumping movements make it hard for players to target them.
The Husk is a special ranged Zed that shoots fireballs out of its arm launcher. It will lock onto a player, and shoot them with great accuracy after charging for a short time. It is possible to dodge a Husk's shot as it has a slow travel time and the Husk's moving target compensation can be tricked with proper timing. A high level Firebug is entirely immune to damage the Husk's shots, though the force of the blow will still be felt and the Husk's melee attack will still do damage.
The Husk was not found in the original mod, although models of a similar Zed was found in the files.
The Siren is a ranged Zed that inflicts damage with her voice. When a Siren comes within range of a player, it will starting screaming, affecting all in a small radius around her. Her voice will also distort a player's vision, and will go through armor to damage a player's hitpoints directly. A grenade thrown at a screaming Siren will simply disintegrate, damaging no one. It is possible to damage a Siren with grenades if all players are far enough away that the Siren's aggro would not cause it to scream.
The Siren is a clone of Kevin Clamely's wife, who wanted to be a singer but lacked talent.
The Scrake is a dangerous Zed that wields a chainsaw in place of its right arm. It is normally not very fast, but will become enraged when its hitpoints fall below a certain percentage (based on difficulty). When enraged, it will chase down a player and saw them until they die, then move on to the next.
The Scrake was supposed to be a field medic that can work on their patients while taking large amounts of pain.
The Fleshpound is the most dangerous normal Zed in Killing Floor, and can deal tremendous amount of damage in an instant. It moves faster than other Zeds, and can become enraged when it takes a certain amount of damage without attempting to strike a player (This meaning that a player can resent the Fleshpound's rage buildup by inciting it to strike the player) or sees a player continuously for some time. When enraged, it will chase down a player and strike them once with their powerful arms. On higher difficulties, that can mean instant death.
Kevin Clamely, mad with power, tasked his scientists to change him into this form: the Patriarch. He appears in the final boss wave, and players must take him down to win the game. He has a chaingun and rocket launcher on his right arm, and a tentacle attached to his torso, which he uses to attack players. He can cloak better than Stalkers, and has 3 health vials which he uses when his health gets low. He can call upon additional Zeds to aid him in battle, which he does every time he goes to heal.
All players in Killing Floor spawn with a set of equipment: a knife, a 9mm pistol, a medical syringe, a welder, and some grenades. Additional weapons must be found in the maps or bought at the Trader after a wave.
Each weapon has a cost, measured in Pounds (£), and a weight, counted in blocks. Every player has a maximum of 15 blocks (up to 24 for Support Specialists), and can only carry weapons up to their inventory limit.
Weapons are divided by perks, and perked characters receive discounts for their respective types of weapons. Higher level perks can spawn with additional weapons or equipment.
Most weapons have an alternate fire, which activates a secondary ability like heavy attacks or flashlights.
9mm Pistol (£150, 4 blocks for akimbo) - Semi-automatic tactical pistol. Although its damage output is overall weak, it is cheap to refill, has decent magazine size, has little recoil, and is good with headshots against weaker enemies. Alternate Fire toggles a built-in flashlight, which has a rechargable battery (that turns off automatically after some time). A 9mm Pistol is starting equipment for all players and cannot be dropped manually or sold. Players can pick up another 9mm Pistol (either dropped by dead teammates, spawned randomly on maps, or bought from the Trader) to dual-wield (sacrificing accuracy for double magazine size). Sharpshooters have increased headshot damage, recoil, and reload speed (conversely with their rank).
Knife - A standard combat knife. Despite its weak damage, it has a very fast attack rate and can easily decapitate weak enemies. Pressing Alternate Fire does a slower heavy slash that deals more damage. Players who equip the knife have a faster movement speed. Starting equipment for all players. Cannot be dropped or sold. Berserkers have increased damage, attack speed, and movement speed (with the Knife equipped) (conversely with their rank).
Grenades (£40, 1 block) - Simple timed grenades that is thrown to clear groups of Zeds. Grenades are thrown with their own separate button and do not need to be equipped manually. Zeds at later difficulties will actively try to avoid thrown grenades. Each player has a limited number of grenades and must replenish them either by picking up ammo boxes (spawned randomly in maps) or by purchasing from the Trader. Cannot be dropped or sold. Grenades thrown by Firebugs (at ranks 3-6) inflict enemies on fire (dealing slightly less damage), while grenades thrown by Field Medics (after the Hillbilly Horror Halloween Event) create a temporary green smoke cloud that heal all allies in the blast radius (while keeping enemies away, dealing slightly less damage in the initial blast). Support Specialists and Demolitions have increased damage and capacity (conversely with their rank).
Medical Syringe - A syringe tool with a small, replaceable container filled with healing fluids. Pressing Primary Fire near a teammate (that does not have full health) heals 20 of the teammate's HP (at the cost of 50 charge), while pressing Alternate Fire heals the wielder for 20 HP (at the cost of 100 charge). The charge indicator recharges over time. Starting equipment for all players. Cannot be dropped or sold. Field Medics get increased recharge speed and injection health (conversely with their rank).
Welder - A portable welding tool used to block doors and gates against Zeds (forcing them to either beat down the door or find an alternate route). Holding down Primary Fire welds while holding down Alternate Fire un-welds. Multiple players can weld or un-weld the door simultaneously to speed up the process. Both welding and un-welding takes up the tool's battery, which recharges over time. Starting equipment for all players. Cannot be dropped or sold. Support Specialists get increased welding speed (conversely with their rank).
Combat Armour (£300) - Passive damage absorption equipment, providing players with additional layer of HP. Armor fully absorbs the damage and effects of both Bloat bile and fire, but does not absorb any damage from Siren screams and fall damage. Spawns randomly on maps. Can be repaired between waves for less money. Cannot be dropped or sold. Starting equipment for Field Medics (ranks 5 and 6), Berserkers (rank 6 on Beginner, Normal, and Hard difficulties), and Firebugs (rank 6). Field Medics get both a huge discount and increased damage resistance (conversely with their rank).
All melee weapons have a movement speed boost when equipped, and have an alternate fire consisting of a large swing, which is slower but deals more damage.
Machete (£100, 1 block) - A simple, lightweight melee weapon that deals more damage than the standard Knife (albeit slightly slower in attacking). Spawns randomly on maps.
Fire Axe (£150, 5 blocks) - A heavy fire axe that deals more damage than the Machete, but is slower to swing. Alternate fire is a large swing that deals more damage. Spawns randomly on maps.
Katana (£1000, 3 blocks) - A lightweight sword that combines fast attacking speed (almost as fast as the Knife) with powerful damage (roughly half-way between Machete and Fire Axe). A golden variant can be purchased after getting the Golden Weapons Pack DLC.
Chainsaw (£1000, 8 blocks) - A loud, heavy chainsaw that provides a powerful constant attack stream (with the exception of alternate fire, which provides a more powerful swing). Eliminates the melee speed boost when equipped, though the increase in damage is kept. A golden variant can be purchased after getting the Golden Weapon Pack 2 DLC.
Scythe (£1250, 6 blocks) - A heavy scythe that has the most powerful melee swing in the game, but also the slowest melee swing. Can only be purchased if the player has bought the Community Weapons Pack DLC.
Claymore (£1500, 6 blocks) - A heavy greatsword that sacrifices attacking speed (matching with the Fire Axe) for brutal damage output and long reach.
Dwarfs?! Axe (£1500, 6 blocks) - A heavy battle axe that functions similarly to the Claymore (with shorter reach), only that each direct hit knocks enemies afar (with exception to larger enemies which are only pushed slightly until killed). Can only be purchased if the player has either purchased Dwarfs!? or acquired an accumulative 40,000 Gold in the free-to-play version of Dwarfs!?.
Buzzsaw Bow (£2500, 7 blocks) - A specialized crossbow that fires spinning buzzsaws, which cuts through multiple enemies and bounce off surfaces multiple times. Like the Compound Crossbow, players can recover the expensive buzzsaws by picking them up. Has a 2x headshot multiplier (3x with the Sharpshooter class). Can only be purchased if the player has bought the Community Weapons Pack DLC.
All Assault Rifles and Battle Rifles can be toggled between fully-automatic (default) and semi-automatic (increases stability and accuracy) by pressing the Alternate Fire button.
Bullpup (£400, 6 blocks) - A modified L22 carbine (with a holographic sight) and the cheapest assault rifle in the game. It has the weakest damage-per-shot out of all assault rifles and battle rifles, but it has the fastest reload speed (and a large magazine size).
Tommy Gun (£900, 5 blocks) - A sub-machine gun (with iron sights) that is lighter than most assault rifles. Although it is slightly cheaper than the AK-47, it deals slightly less damage. Can only be purchased if the player has bought the Community Weapons Pack DLC.
AK-47 (£1000, 6 blocks) - A standard assault rifle (with iron sights) that deals almost double the damage per shot than the Bullpup (at the cost of lower magazine size). A golden variant can be purchased after getting the Golden Weapons Pack DLC. A neon-themed variant can be purchased after getting the Neon Weapon Pack DLC.
M4 (£1000, 6 blocks) - A standard assault rifle (with a red dot sight) that has identical stats to the AK-47, with the exception of a larger ammo capacity, better accuracy, less damage per shot, and the inclusion of a scope (that, when viewed down-the-sights, provides better zoom and steadier aim at the cost of being more obtrusive). A digi-camo variant can be purchased after getting the Camo Weapon Pack DLC.
MKb42 (£1100, 6 blocks) - A standard assault rifle (with iron sights) that has identical stats to the AK-47, with the exception of its slightly greater cost, less recoil, and greater accuracy.
SCAR Mk.17 (£2500, 5 blocks) - An expensive battle rifle (with a red dot sight) that deals heavier damage per shot (than its cheaper counterparts), at the cost of more expensive ammunition, lower magazine size, and higher recoil. It is also slightly lighter than most assault rifles. A neon-themed variant can be purchased after getting the Neon Weapon Pack DLC.
FN FAL ACOG (£2750, 6 blocks) - An expensive battle rifle (with an ACOG scope) and the most expensive out of all Commando weapons. It has the same powerful stats to the SCAR Mk.17, with the exception of higher rate-of-fire, lower recoil, slightly heavier weight, higher cost, and the inclusion of an ACOG scope (that, when viewed down-the-sights, provides better zoom and steadier aim at the cost of being more obtrusive).
All Medic Guns (except the Blower Thrower Bile Launcher) can fire a special med-dart (by pressing the Alternate Fire button) that heals allies (in similar vein to the Medical Syringe) that it hits. While med-darts can be used to heal allies in range and has a separate charging functionality (allowing players to use their Medical Syringe alongside charging med-darts), players can not heal themselves with them.
All Medic Guns are also very expensive for those who are not Field Medics.
M99 AMR (£3500, 13 blocks) - A very expensive, very heavy, and very powerful sniper rifle. Its unbelievable headshot damage allows it to instantly kill most specimen in most situations. Despite being able to penetrate through enemies, each round is extremely expensive (£250 each).
These weapons are perk-neutral, as no classes have any additional benefits with them.
Since its original release, Killing Floor has been supported with both free updates and paid downloadable content. Upgrading the game to the latest version adds all content (including paid ones). However, the paid content are locked and are only selectable for players who purchased the content.
The game, plus the first six character packs, was re-released in boxed form as Killing Floor: Gold Edition. Exclusive to this retail version (released online for $29.99 on June 1, 2012) is a timed exclusive of a new female character (Ash Harding), who comes with three female voice packs (English, French, and German) and was released as a special character pack on August 1, 2012.
As of December 2, 2014, players can purchase paid DLC in bundles, including the Character Pack Bundle ($29.99, includes the first seven character packs), the Premium Character Bundle ($19.99, includes the last seven character packs), Weapons Bundle ($29.99, includes all weapon packs and weapon skin packs), and Community Content Bundle ($19.99, includes all three community weapon packs, the Neon Weapon Pack, and the Neon Character Pack).
Outbreak Character Pack - Released on July 24th, 2009 for $1.99. Unlocks four playable characters: Agent Wilkes, Foundry Worker Albridge, DJ Scully, and Dr. Gary Glover. Also included in the Gold Boxed Edition.
Nightfall Character Pack - Released on October 22nd, 2009 for $1.99. Unlocks four playable characters: Mr. Foster, Security Officer Thorne, Lance-Corporal Lee Baron, and Mike Noble. Also included in the Gold Boxed Edition.
Postmortem Character Pack - Released on October 7, 2010 for $1.99. Unlocks four playable characters: Harold Hunt, Kerry Fitzpatrick, Trooper Clive Jenkins, and Paramedic Alfred Anderson. Also included in the Gold Boxed Edition.
"London's Finest" Character Pack - Released on December 14, 2010 for $1.99. Unlocks four playable characters: Chopper Harris, Kevo the Chav, Captain Wiggins, and Reverend Alberts. Also included in the Gold Boxed Edition.
Steampunk Character Pack - Released on July 2, 2011 for $1.99. Unlocks four playable characters: Reggie "Basher" Clover, Adam Butler, Doctor Dave, and Peter the Assassin. This pack was also available to unlock for 3 tickets via Steam's Summer Camp promotion lasting from June 30th to July 10th, 2011. Also included in the Gold Boxed Edition.
Steampunk Character Pack 2 - Released on December 7, 2011 for $1.99. Unlocks four playable characters: Steampunk DJ Scully, Steampunk Demolition, Steampunk Support Specialist, and Steampunk Commando. Also included in the Gold Boxed Edition.
Urban Nightmare Character Pack - Released on July 5, 2012 for $1.99. Unlocks four playable characters: Dave "The Butcher" Roberts, Dr. Jeffrey Tamm, Fireman Sam Avalon, and Shadow Ferret.
Harold Lott Character Pack - Released on July 5, 2012 for $4.99. Unlocks one playable character: Harold Lott.
Ash Harding Character Pack - Released on August 10, 2012 for $4.99. Unlocks one playable character: Ash Harding. This character was originally exclusive to the Gold Boxed Edition of Killing Floor (which was released on June 1, 2012) and includes three new female voice packs for the character (in English, French, and German).
The Chickenator Pack - Released on October 23, 2012 for $4.99. Unlocks one playable character: The Chickenator.
Robot Special Character Pack - Released on December 13, 2012 for $4.99. Unlocks one playable character: Domestic Assistance Robot (D.A.R.), who includes its own robotic voice pack.
Starting with the 2012 Halloween event, Tripwire has released several new weapons that have been designed and developed by the community. All profits made from the DLC go towards the creators of each weapon. These weapons are unique (in some shape or form) from other weapons, and can be dropped for (and picked up by) players who did not purchase the pack.
Starting with the 2012 Christmas event, Tripwire has released several cosmetic packs for existing weapons. These weapons have no unique properties or stats and can be dropped for (and picked up by) players who did not purchase the pack.
The Ball - Players who pre-ordered The Ball (prior to its October 26, 2010 release) received the game's protagonist in Killing Floor (given the name Harchier Spebbington). After December 5, 2013, players who own the game receive an alternate version of Spebbington.
Team Fortress 2 - Players who own both Killing Floor and Team Fortress 2 (prior to January 4, 2011) received two bonus characters in Killing Floor: RED Pyro and BLU Pyro. (In contrast, players also receive promotional cosmetic gear for the Pyro in Team Fortress 2 resembling Mr. Foster).
Red Orchestra 2: Heroes of Stalingrad - Players who purchase the Steam Digital Deluxe Edition of Red Orchestra 2: Heroes of Stalingrad receive two bonus characters: World War II re-enactors Nikolay (wearing a Russian uniform) and George (wearing a German uniform).
Since the game's release, free updates have been released as downloadable content. Along with the standard gameplay tweaks and enhancements, all of these updates add new maps to the base game. Most of these updates also add new weapons and Steam achievements, as well as special seasonal tweaks (such as enemy appearance).
Heavy Metal Content Pack - Released on August 20th, 2009. Added one new map (Foundry) and two new weapons (AK-47 and Katana).
Level Up Content Pack - Released on October 22nd, 2009. Added one new perk (the Demolition perk), a sixth level to all perks, three new maps (Bedlam, Wyre, and Waterworks), a new specimen (the Husk), seven new weapons (MP7 Medic Gun, AA12 Auto Shotgun, M14 Enhanced Battle Rifle, SCAR Mk17 Assault Rifle, Pipebomb Proximity Charge, M79 Grenade Launcher, and M32 Multiple Grenade Launcher), and new Steam achievements.
Grindhouse Competition Pack - Released on December 11, 2009. Added four new maps: Icebreaker, Departed, Crash, and Filth's Cross.
Incendiary Content Pack - Released October 7, 2010. Added four new maps (Hospital Horrors, Biohazard, Mountain Pass, and Suburbia), one new weapon (MAC-10), and a new system for rewarding money (percent of damage done).
Twisted Christmas Event (2010) - Released on December 14, 2010. Added one new map (Santa's Evil Lair), one new unlockable character (Bill "Baddest Santa" Weeks), new Steam achievements, and a new "hardest" difficulty setting (Hell on Earth). Temporarily re-skinned all monsters with the Twisted Christmas theme.
Potato Sack Promotion - Released on April 12, 2011. Added one new map (Aperture), one new temporary shop item (the expensive £70000 Potato, which only grants an achievement to everybody in the server), a temporary Trader replacement (GlaDOS), and new Steam achievements. The map is based on Portal 2, as the game was part of the Potato Sack promotion.
Summer Sideshow Event (2011) - Released on June 30, 2011. Added one new map (Abusement Park), one new unlockable character (Steampunk Mr. Foster), and new Steam achievements. Temporarily re-skinned all monsters with the Summer Sideshow theme.
Halloween Sideshow Event (2011) - Released on October 27, 2011. Added new Steam achievements and one new unlockable character (Commando Chicken). Temporarily re-skinned most monsters with the Halloween Sideshow theme.
Twisted Christmas Event (2011) - Released on December 7, 2011. Added one new map (Ice Cave), six new weapons (Scottish Claymore, M-4 Carbine, M-4 Carbine with M-203 Grenade Launcher, Combat Shotgun, Husk Fireball Launcher, and MP5 Submachine Gun), and new Steam achievements. Temporarily re-skinned all monsters with the Twisted Christmas theme.
Summer Sideshow Event (2012) - Released on July 5, 2012. Added one new map (Hellride), five new weapons (Mk. 23 Pistol, FN FAL Assault Rifle with ACOG Scope, M7A3 Assault Rifle, HSG-1 Auto Shotgun, and M99 Marksman Rifle), and new Steam achievements. Temporarily re-skinned all monsters with the Summer Sideshow theme.
Hillbilly Horror Halloween Event - Released on October 23, 2012. Added one new map (Hillbilly Horror), three new weapons (Dragon's Breath Trenchgun, Vlad 9000 Nailgun, and MKb42(h) Assault Rifle), new Steam achievements, and one new unlockable character (The Grim Reaper). Temporarily re-skinned all monsters with the Hillbilly Horror theme.