The Alien Swarm wiki last edited by mento on 12/21/15 08:48AM View full history


Alien Swarm is a top-down multiplayer co-operative shooter that pits up to four players against swarms of alien drones, explosive "boomers", and infectious parasites. It was originally released in May of 2004 as a total modification for Unreal Tournament 2004. The development team then was hired by Valve, who then began working on several games including Left 4 Dead and Portal 2 while porting the mod to Valve's Source engine as a side project. The game, as well as the source code and SDK, was released on July 19, 2010 for free to all PC Steam users.

The game features persistent player statistics, an experience system, unlockable weapons and items, a prestige system similar to Call of Duty 4, and 64 Steam achievements. One achievement gives the player a hat for all classes in the PC and Mac versions of Team Fortress 2 that resembles the parasite.


 The squad loadout screen, where players must determine what classes, items, and weapons to use.
The squad loadout screen, where players must determine what classes, items, and weapons to use.

Alien Swarm requires tactics and cooperation between the members of the marine squad. There are eight characters to choose from, two for each class (Medic, Technician, Explosives Officer, and Special Weapons). Each class brings unique equipment and abilities to the squad. The Medic has the ability to heal other marines. The Technician hacks important switches and computer consoles and carries a scanner that automatically detects aliens on the radar. The Explosives Officer has improved explosive weapons and items, comes with a "leadership" property (which gives a bonus to damage and damage resistance to nearby allies), and can carry the Vindicator, a powerful shotgun that can shoot incendiary grenades. The Special Weapons class can carry powerful gattling guns and has piercing, more damaging bullets. Some missions require at least one Technician, who must survive until all required hacking challenges are complete.


The game features 2 Officers, 2 Medics, 2 Techs, and 2 Special Weapons Marines.

  • Medic #1: Corporal Eva ' Faith' Jensen : A caring and empathetic person, she wants her team to survive the mission.
  • Medic #2 : Private Leon Bastille AKA "The French Man" : Born into a criminal world, Leon is the best combat medic.
  • Tech #1: Private David ' Crash' Murphy : The best in terms of hacking, has a country, southern accent.
  • Tech #2 : Vegas : A gambler in his previous life, now he serves the IAF to escape those who want to collect on old debts.
  • Special Weapons #1: Private Thomas Wolfe : Ex-convict turned Special Ops through the court system, He excels with the chain gun.
  • Special Weapons #2: Wildcat : Former colonist survivor but after they were taken by the swarm, she now seeks to destroy them all.
  • Officer #1: Master Sergeant Joseph ' Sarge' Conrad : A leader with long term experience against the swarm, Conrad brings the best out of his team.
  • Officer #2: Corporal Karl Jaeger : Jaeger has a warrior's passion, he enjoys being in the thick of battle and would love to see his life end that way.

Weapons and Equipment

Alien Swarm features a loadout configuration system consisting of two weapon slots and one item slot per player. Most of these require the player to level up by playing the game.

Weapon Slot

  • 22A3-1 Assault Rifle - Standard-issue assault rifle with frag grenade launcher.
  • 22A7-Z Prototype Assault Rifle - (Tech only) Same as the standard assault rifle, with the addition of auto-aim capabilities and a stun grenade launcher in place of a frag grenade launcher.
  • S23A SynTek Autogun - (Special Weapons only) Portable gatling gun with auto-aim capability.
  • M42 Vindicator - (Officer only) Pump-action shotgun that can also fire incendiary grenades.
  • M73 Twin Pistols - Dual pistols used for ammo efficiency.
  • IAF Advanced Sentry Gun - Deployable automatic sentry gun with standard autocannon.
  • IAF Heal Beacon - (Medic only) Creates a beacon that heals all marines inside.
  • IAF Ammo Satchel - Deployable ammo packs.
  • Model 35 Pump-action Shotgun - (unlocked at level 3) Powerful close-range double-barreled shotgun.
  • IAF Tesla Cannon - (unlocked at level 5) Electric weapon that stuns enemies before killing them, arcs to other enemies, and avoids friendly fire.
  • Precision Rail Rifle - (unlocked at level 7) Railgun with high accuracy and armor-piercing rounds.
  • IAF Medical Gun - (Medic only, unlocked at level 9) Similar to the Medigun from Team Fortress 2. Fires a healing beam at other players. The marine can also use it to heal himself.
  • K80 Personal Defense Weapon - (unlocked at level 11) A pair of submachine guns designed for extreme damage at the cost of high ammo usage.
  • M868 Flamer Unit - (unlocked at level 13) General-purpose flamethrower. However, alternate firing of this weapon extinguishes fires.
  • IAF Freeze Sentry Gun - (unlocked at level 15) Deployable automatic sentry gun that fires liquid nitrogen, temporarily freezing enemies.
  • IAF Minigun - (Special Weapons only, unlocked at level 17) Similar to the Minigun from Team Fortress 2. Creates a wide blanket of fire. Alternate fire spins up the barrel without firing.
  • AVK-36 Marksman Rifle - (unlocked at level 19) Semi-automatic sniper rifle.
  • IAF Incendiary Sentry Gun - (unlocked at level 21) Deployable automatic sentry gun with incendiary bullets and faster enemy tracking.
  • Chainsaw - (unlocked at level 23) Standard chainsaw with unlimited ammo.
  • IAF High Velocity Sentry Cannon - (unlocked at level 25) Deployable automatic sentry gun with slugs that can travel far and create splash damage.
  • Grenade Launcher - (unlocked at level 27) Handheld grenade launcher.
  • Fire Extinguisher - (found in SynTek Residential) Standard fire extinguisher used to put out fires.
  • Mining Laser - (found in Timor Station) Powerful laser that cuts through rocks and biomass.

Item Slot

  • IAF Personal Healing Kit - A small medkit developed for one-time use on the marine carrying the item.
  • Hand Welder - A welder that is used to weld and unweld certain doors.
  • SM75 Combat Flares - A set of flares used not only to light up areas, but provide an auto-aim bonus.
  • ML30 Laser Trip Mine - A pack of throwable proximity mines that blow up when any hostile passes its laser beam.
  • 13a Tactical Heavy Armor - (unlocked at level 2) Marines carrying this item automatically receive 20% less damage.
  • X33 Damage Amplifier - (unlocked at level 4) Creates a beacon that doubles damage for all marines inside.
  • Hornet Barrage - (unlocked at level 6) Unleashes a barrage of homing missiles.
  • Freeze Grenades - (unlocked at level 8) Grenades that temporarily freezes enemies upon impact.
  • Adrenaline - (unlocked at level 10) Temporarily activates slow-motion.
  • IAF Tesla Sentry Coil - (unlocked at level 12) Deploys a tesla coil that stuns enemies within a certain radius.
  • v45 Electric Charged Armor - (unlocked at level 14) Electric blast that stuns attackers and removes infection of parasites from the user.
  • M478 Proximity Incendiary Mines - (Officer only, unlocked at level 16) Releases a line of fire to either side of the mine.
  • Flashlight Attachment - (unlocked at level 18) A automatic flashlight attached to the top of the weapon.
  • IAF Power Fist Attachment - (unlocked at level 20) Automatically doubles melee damage of the user.
  • Hand Grenades - (unlocked at level 22) A set of highly explosive cluster grenades.
  • MNV34 Nightvision Goggles - (unlocked at level 24) Rechargeable night-vision goggles.
  • MTD6 Smart Bomb - (unlocked at level 26) Causes a stream of homing rockets to fire over a wide area.
  • Assault Jets - (must be found in-game) Allows the player to perform large boosted jumps, crushing or pushing back aliens in landing.
  • Blink Pack - (must be found in-game) Allows the player to teleport through enemies and certain walls.


  • Drone - The most common enemy found in the game. Weak on their own, they usually attack in large numbers. Drones can also leap across gaps, sometimes past defenses.
  • Ranger - Starting from Deima Surface Bridge, these acid-firing aliens will start appearing. They will fire three acid pellets at the direction of a marine, which can be rolled under.
  • Shield - Starting from Deima Surface Bridge, these massive aliens will occasionally appear. They are powerful close-range attackers with a large shield in the front (its front legs) that can often block attacks.
  • Buzzer - Starting from Rydberg Reactor, these small, agile aliens will become an issue. They do little damage, but can fly and mess up a player's camera when attacked.
  • Boomer - Starting from Rydberg Reactor, these large tripedal aliens will begin to show up. They do not attack directly, instead inflating when they see a marine. Destroying an inflated boomer will cause explosive bombs to shoot out of its body.
  • Parasite - Starting from SynTek Residental, the parasite makes itself known. They are weak, but fast, and will infest marines that they manage to jump on. They can be the most powerful enemies in the game, as countering infestation requires much healing (or the use of a electric charage armor). They are often found inside swarm eggs.
  • Grub - Harmless little aliens that are found around swarm eggs. Bullets do no damage, but they can be stomped.
  • Mortar - Found in Sewer Junction B5 and Timor Station, the Mortar bug is a large enemy that shoots three acid bombs (similar to the Boomer) at marines at a time.
  • Harvester - Found in Timor Station, the Harvester releases small bugs that look similar to parasites. These small bugs do not infect, instead exploding for high damage.


Alien Swarm comes with one seven-map campaign, titled "Jacob's Rest", in which a marine squad of the Interstellar Armed Forces must investigate a colony on Vereon XII that is overwhelmed by aliens.

  • Landing Bay - Sweep the landing bay and retrieve flight data from an escape pod.
  • Cargo Elevator - Proceed through the central cargo elevator to the colony.
  • Deima Surface Bridge - Locate a pipeline compromised by the swarm.
  • Rydberg Reactor - Gain access to the reactor control room and bring it back online.
  • SynTek Residential - Search and destroy swarm eggs and biomass. (Flamethrower required for mission)
  • Sewer Junction B5 - Explore the underground sewer passages while destroying swarm eggs.
  • Timor Station - Locate the nuclear warhead and detonate it at the entrance to the alien hive.

Alien Swarm SDK


The Alien Swarm SDK (also known as the Alien Swarm Authoring Tools) was released along with the original launch of the Steam version of Alien Swarm. It is a special version of the Source SDK, including a suite of tools used for developing for Alien Swarm. The SDK also includes the full source code for the game, which includes updates to the Source Engine and full Steamworks integration.

While the SDK allows the player to build maps in Valve's Hammer utility, it comes with a special experimental tile-based level generator called TileGen; which allows level designers to create level arrangements using predefined rooms (in a similar fashion to the MapMaker mode in the TimeSplitters franchise). TileGen can also use predefined "mission generation rules" to randomly generate a level. More information about TileGen can be found here.

System Requirements

Minimum: Recommended:
  • OS: Windows® 7 / Vista / Vista64 / XP
  • Processor: Pentium 4 3.0GHz
  • Memory: 1 GB for XP / 2GB for Vista
  • Graphics: DirectX 9 compatible video card with 128 MB, Shader model 2.0. ATI X800, NVidia 6600 or better
  • Hard Drive: At least 2.5 GB of free space
  • Sound: DirectX 9.0c compatible sound card
  • OS: Windows® 7 / Vista / Vista64 / XP
  • Processor: Intel core 2 duo 2.4GHz
  • Memory: 1 GB for XP / 2GB for Vista
  • Graphics: DirectX 9 compatible video card with Shader model 3.0. NVidia 7600, ATI X1600 or better
  • Hard Drive: At least 2.5 GB of free space
  • Sound: DirectX 9.0c compatible sound card

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