The IAF Bible

This guide is essentially my journal of things I have found out about Alien Swarm. Featuring undocumented functionality, explainations of gameplay features, and fixes for known buggy behaviour.

This guide is currently unfinished so do check back occasionally to see if there's anything new that's been added in.

If you're viewing this for the first time, please check the sections on:

1. Friendly Fire
   
2. The Flamer Unit
   
3. Commands & Convars, as the listed config fixes some minor issues.
   
4. "How do I get the TF2 Hat?"
   
5. Finding Other Players

This section is a collection of statements I make throughout the IAF Bible. I think putting them at the very start is important, since that's where people are most likely to actually see them.

These polite guidelines primarily concern public lobbies. You're fine to act however you wish in private lobbies, however in the interest of keeping the game alive and ensuring new players have a good experience, please act in accordance with what is below:

1. Don't be a ♥♥♥♥: Don't rush ahead and get yourself killed; Don't rush ahead and get the rest of your team killed; Don't blindly scoff ammo resupplies
   
2. Don't try to do everything: Respect the roles other marines fufill; Don't deliberately overextend when you aren't a frontline class; Don't blindly carry your team
   
3. Do not ruin fun: Don't be overbearing on newer players; Don't trivialise lower difficulties with high level unlocks; Don't abuse bugs or glitches when other players are playing normally

When navigating to Play Online -> Find Public Games you'll see a matchlist similar to Left 4 Dead. This matchlist is a collection of every public dedicated server or listen server with at least one person and at least one free player slot remaining.

Most of the time you will be connecting to listen servers. Listen servers are gameservers that are run alongside an instance of the game, i.e: on another player's system. When you create a new lobby by using the Create New Game button in the matchlist or Play Online -> Craete Game, you are creating an ephemeral listen server that runs on your system.

The player running the listen server is in ultimate control of the server, even if another lobby leader is selected. The lobby leader controls when the mission starts, nothing else.

If the player running the listen server exits the game, the listen server will shutdown and all players will be booted back to the main menu. Alien Swarm is supposed to try to find another player to host the listen server but it doesn't actually do that in practice.

Unlike other sources game such as TF2 or Garrys Mod, custom maps cannot be automatically downloaded and have to be installed manually. See Mods & Custom Campaigns for details.

Lobbies can be either public, meaning they can appear in the matchlist to all Alien Swarm players, or friends only, meaning they will be hidden from the matchlist. Lobbies in friends only mode can still be joined if you are friends with any player currently in the lobby.

While there is no UI to switch between public and friends only, you can do so using the console commands make_game_public and make_game_friends_only.

Alien Swarm has four distinct classes that each have their own unique equipment. For the most part, the class you play does not matter beyond the equipment they can use. Instead, each marine is distinquished by the skills they have.

You should get the feel as to which marines you need played as you fail missions. If you're slowly running out of health over time, you'd possibly want a medic like Bastille, that can heal any small hits you take. If parasites are killing your team often or your team is frequently taking a lot of damage, Faith's heal efficiency would help the most.

Getting overrun by swarm when moving ahead can be alleviated by having a frontliner like Sarge, Jaeger, or a Special Weapons marine like Wildcat or Wolfe.

Do note that the below list is only relevent if you are playing with the default skill points. If you have custom skill points enabled, each marine's skill in the categories they have will be zero, but can be leveled up over time by completing missions.

Officers excel in dealing burst damage. Officers also apply a buff to nearby marines that both increases their resistance to damage and increases the damage they deal.

Sarge:
Sarge excels as a frontliner that may need tank some occasional hits. Sarge has excellent survivability thanks to his high health pool and damage resistance buff that he shares to nearby marines.

• Applies a strong buff to nearby marines. Sarge applies the strongest buffs in the game
  
• Has a small damage bonus for the Vindicator
  
• Has a small damage bonus for explosives
  
• Has a strong health bonus. Sarge has the most health in the game
  
• Has a moderate damage bonus

Jaeger:
Jaeger excels when paired with the Vindicator and explosives.

• Applies a moderate buff to nearby marines
  
• Has a strong damage bonus for the Vindicator. Jaeger does the most Vindicator damage in the game
  
• Has a strong damage bonus for explosives. Jaeger does the most explosive damage in the game
  
• Has a moderate health bonus
  
• Has a small melee damage bonus

Heavies can use the Autogun and Minigun, which can mow down swarms of aliens at the cost of burning through ammo.

Wildcat:
No blurb yet.

• Has a moderate damage bonus for the Autogun and Minigun
  
• Has a small piercing bonus, making it more likely her shots will pass through enemies
  
• Has a moderate damage bonus
  
• Has a moderate speed reload bonus
  
• Has a strong speed bonus. Wildcat is the fastest marine in the game

Wolfe:
Wolfe is a slow juggernaught, that when paired with the IAF Minigun, can carve holes through swarms of aliens. Wolfe is the best pick when the Autogun or Minigun is your primary or only weapon.

• Has a strong damage bonus for the Autogun and Minigun. Wolfe does the most damage with Autoguns in the game
  
• Has a moderate piercing bonus, making it more likely his shots will pass through enemies
  
• Has a small damage bonus
  
• Has a small reload speed bonus
  
• Has a moderate health bonus

Techs will highlight nearby enemies and can interact with locked terminals and doors. Techs also apply a buff to nearby marines that makes them unweld doors and place sentries faster.

Crash:
Crash excels as a combat engineer that can also assist in crowd control thanks to his explosives bonus.

• Applies a small engineering buff to nearby marines
  
• Has a moderate damage bonus
  
• Has a moderate speed bonus. Crash is the fastest reloader in the game
  
• Has a small damage bonus for explosives

Vegas:
Vegas excels as a support class, thanks to high engineering buff. When using the Chainsaw, Vegas can quickly tear down doors or kill enemies up close.

• Applies a strong engineering buff to nearby marines. Vegas is the best engineer in the game
  
• Has a moderate health bonus
  
• Has a small reload speed bonus
  
• Has a moderate melee damage bonus. Vegas has the strongest melee damage in the game

Unless disabled through asw_marine_ff 0, friendly fire will always be possible, even when hardcore friendly fire is not enabled.

Alien Swarm clamps how much friendly fire damage can be dealt based on how long you are shooting at an ally. Even a shotgun to the face, which would instantly kill on hardcore, will only deal around 20 dmg.

It is important to note that regardless of if hardcore mode is enabled, a minimum amount of damage is always dealt. Weapons like the flamethrower can kill friendlies without warning if they are at very low health.

Friendly fire is managed by the following cheat convars:

Most all of the aliens you will encounter can be temporarily stunned by firing at them. When an enemy is stunned, they will be unable to attack for a small duration that lowers as the difficulty increases.

Even a single bullet can stun an alien, potentially for long enough for you to hit them with a melee attack to stun them again and land a kill. All weapons, the flamer unit especially, have the ability to stun aliens.

Strategically stunning aliens is a key part of crowd control in Alien Swarm and help you slow an approaching crowd down for long enough that you can gun them down properly.

Some weapons and offhand items can electrify swarm. Electrifying an alien slows them down to a near crawl and prevents them from turning, allowing you to easily get behind them or make some distance between them. Shield bugs are especially vulnerable to being electrified, as their weak spot becomes far easier to attack.

The Tesla Cannon, Tesla Trap, and the Prototype Rifle alt-fire are capable of electrifying aliens. Generally, you'll want to opt for the Tesla Trap or Prototype Rifle over the Tesla Cannon as the penalty of devoting an entire weapon slot to utility is heavy.

By default, marines do not collide with one-another. However, this does not mean you are free to walk into your teammates whenever you like.

While you can phase through other marines, marines still block bullets and projectiles. Standing too close to another marine can easily block their shots or prematurely detonate their grenades, potentially killing them, or you, in the process.

When two marines are running too close to eachother, Alien Swarm has a tendency to pull them together into a blob. This not only blocks both marines from shooting, but also slows both marines down.

It’s best to give fellow marines some space to avoid this. Consider moving in formation or at minimum leaving at least one marine of space between your squadmates.

You can optionally turn on marine collision to make poor formation easier to recognise. The following convar controls this:

All weapons aside from the chainsaw use clips of ammo. Reloading your weapon will discard the clip currently in your weapon and replace it with a new clip, also discarding any unfired rounds that were in the old clip.

During a reload, you can cancel out by switching to another weapon or dropping the weapon you were reloading. By cancelling a reload, you can switch back to the weapon to be able to try reloading again or to fire off any remaining rounds that your current clip had.

Ammo boxes should be shared with other players, do not just spam 'e' and take absolutely everything. It's shocking I even have to state such basic gaming etiquette.

Reloading prior to running dry is good practice since it gives you more control of when you run out of remaining rounds. If you run a clip completely dry, you'll be entirely unable to fire on an enemy without switching to another weapon or successfully reloading your gun. Since being attacked interrupts your reload briefly, running out of rounds at a bad time can easily snowball into a fast death.

Similar weapons share ammo types. Two examples are the Prototype Rifle & Assault Rifle and the Autogun and IAF Minigun. If you spawn in with two weapons of the same ammo type, they will share their ammo reserves. Spawning in with two identical weapons will only spawn you in with one of that weapon, but will still give you twice the ammo clips.

While you may spawn in with more than 5 ammo clips, most weapons are limited to a maximum of 5 clips you can carry. Once you exhaust the excess clips, you'll only be able to carry 5 ammo clips.

Weapons that have less than 5 ammo clips, such as the Autogun and IAF Minigun will actually keep their extra clip slot even after it's been used, increasing the maximum number of clips that gun can hold for the entire map.

If you want to bring more ammo, you'll often be far better off by carrying an Ammo Satchel instead of doubling up a weapon. This will not only allow you to carry far more ammo, it'll also allow you to share ammo with fellow marines.

The M868 Flamer Unit is very ammo efficient and doubles as a fire extinguisher. Given this, many new players gravitate towards it over the standard assault rifle, prototype rifle, or K80 PDW.

I have seen many lobbies with nearly every player using the flamer, and a consequence of this is at higher difficulties they'll quickly end up either out of ammo or swarmed with enflamed drones and suffer a death by a thousand cuts.

Afterburn does not stack so there is very little benefit to having multiple flamer marines on your team. You are far more liable to suffer an increase in friendly fire incidents than an increase in damage and overall combat effectiveness. Always ensure that your squad has a balance of immediate damage (assault rifle, K80 PDW, minigun, etc) to utility (flamer unit, chainsaw, ammo satchel). Too much immediate damage or too much utility will drastically lower the effectiveness of your squad.

The flamer is best used in short bursts and for utility. The flamer lacks the burst damage that weapons like the assault rifle or vindicator do, making it a very poor choice for quickly killing even a single swarm drone. The biggest benefit to the flamer is the slowing effect it has to enflamed drones, an effect that is even present on Brutal.

Misuse of the flamer can quickly result in setting your own teammates on fire. Short controlled bursts can help reduce the likelihood of this, however it's still best to avoid firing near teammates, especially when they are at low health.

An experienced player that knows how to effectively use the flamer can completely trivialise missions on difficulties lower than Insane. If you are such an experienced player, don't use the flamer.

Alien Swarm features semi-functional bots that can be seen in the practice mission. If a player leaves mid-game, the marine they played as will become a bot.

While there is no UI to spawn in these bots, they can be added into multiplayer games with console commands.

The cl_selectm command takes two integer arguments:

1. The numeric ID of the marine you want
   
2. The selection ID where the marine will be placed in the lobby screen

Both the selection ID and numeric ID start from 0. The selection ID can be from 0 to 3, with 0 replacing whatever marine you have selected. If you pull up the marine selection view and count left-to-right from 0, you can determine what marine ID corresponds to which marine.

For convenience, here is a mapping of each marine ID to the name of each marine:

• 0 == Sarge
  
• 1 == Wildcat
  
• 2 == Faith
  
• 3 == Crash
  
• 4 == Jaeger
  
• 5 == Wolfie
  
• 6 == Bastille
  
• 7 == Vegas

To deselect a marine, use the cl_dselectm and the marine ID you want to deselect.

Note: When using commands to add in bots, you will no longer be able to change the marines using the UI. You will need to use console commands or remove all bots present to select using the UI again.

Note: If a mortarbug is present nearby a bot, the bot will get very confused and stand still in place. This is a poor strategy when faced with a mortarbug, and will usually get them killed.

If I wanted to set my own marine to crash, I would run cl_selectm 3 0. If I then wanted to add Bastille and Sarge, I would run cl_selectm 6 1 and cl_selectm 0 2

Then, if I decided that I wanted Jaeger instead of Sarge, I would run cl_selectm 4 1 to replace Sarge with Jaeger. Finally, if I decided I don't want any officer at all, I would run cl_dselectm 4 to deselect Jaeger, leaving me with Bastille as my only bot.

When the mission starts, all bots will decide to follow a (seemingly random) player. You can command your assigned marines by using the GO and HOLD gestures.

You can switch between your assigned marines by using the F1, F2, F3, and F4 keys.

The +holdorder command is an undocumented command that you can bind to a key to tell a bot to go somewhere. The +holdorder command only works for bots you have created. You can't issue a hold order to a marine assigned to another player.

You can bind +holdorder to a key on your keyboard by using the bind command:

Now, by holding the b key, you will be able to tell a bot exactly where to stand and where it should face.

When multiple bots are in your lobby, you will have to call +holdorder (press b) twice. First to select the bot you want to move, and second to tell it where to actually go.

Alien Swarm features an unused campaign system that shoves useless .campaignsave files into your save directory. The convars asw_campaign_death and asw_campaign_wounding both use this campaign system and can be used to optionally enable marine death and wounding for an extra challenge.

asw_campaign_death functions fairly simply. When a mission is completed, any marines that died during that mission are permanently dead for the rest of the campaign.

Dead marines will still show up as selectable, but when clicked will instead switch you to the marine silhouette that is shown when you have no marine selected. The player that was playing the now-dead marine will be switched to the marine silhouette when the lobby loads in.

The host (possibly the leader, needs testing) can revive all dead marines by running cl_revive.

asw_campaign_wounding is a bit more complicated. If a mission is completed, any marines that have taken a significant amount of damage will have their health halved for the next mission, even if they were healed back up to full health afterwards.

When a marine is wounded, there are two ways they can be alleviated of the wounded state:

1. If the marine is not played for one mission, they will no longer be wounded.
   
2. If the marine is played for one mission but does not take any significant damage, they will no longer be wounded.

The cl_revive command does not unwound marines.

Maintaining distance is a simple way to avoid damage from swarm drones. Drones are the primary alien you'll be shooting and they can only deal damage at close range. A marine on the otherhand can deal damage from a much safer distance.

Slowly retreating backwards when a large swarm is rushing towards you can buy you enough time to pick them off, or enough time for another marine to help cover you. Unless you're explicitly using a weapon that works at close range, such as the chainsaw, you shouldn't be within hugging distance of enemies.

Simplification in chess is the act of making the game less complicated by exchanging one or multiple pieces with your opponent. With fewer pieces on the board, fewer variations are left to be calculated by each player, simplifying the game. — ♟ Chess (dot) com[www.chess.com]

Simplification is a chess term for simplifying the playing field by reducing the number of variables you have to consider, thus reducing the likelyhood you will make an unforeseen mistake. This game theory can be applied in many places, including in video games, and including in Alien Swarm.

Simplification can be applied in various ways:

1. Focusing down enemies that complicate fights such as harvesters, buzzers, mortar bugs, and shield bugs.
   
2. Repositioning to reduce the number of directions enemies can approach from.
   
3. Retreating to a previously cleared area instead of fighting in an area you are less familiar with.

If you are struggling with getting overwhelmed, applying simplification can make dealing with even large swarms of enemies far easier. You will get cornered less, get interrupted while reloading less, and take less damage.

You get the TF2 hat through the process of completing the campaign. If you want the hat, just play the game. When you unlock the achievement Hat Trick, you'll receive the Parasite Hat the next time you start TF2.

Literally just play the game for an hour or so and you'll get it. The same advice goes for most of the other achievements.

A lot of more experienced or veteran players will often play in ways that optimise for solo play and seemingly ignore that Alien Swarm is a co-op game.

Abusing the flamer on lower difficulties, running away from the rest of your squad, or spamming grenades everywhere may be fun for you, but that enjoyment comes at the cost of the rest of your team. Having a 4000 hour "IAF god" clear the entire map and leave nothing for other players to do is very toxic behaviour, especially when playing with brand new players that will leave with the impression that your bastardisation of Alien Swarm is how the game is intended to be played.

Speedrunning can be fun. Exploiting the imbalance of weapons can be fun. You should not have fun at the cost of depriving other players of fun. Stick with your squad and help keep new players alive. That is how the game is intended to be played, and it can be far more entertaining and fun than spamming grenades so hard a spectator could mistake it for an earthquake.

I would suggest the following convars be set in autoexec.cfg as they either fix problems or unlock functionality.

If you don't have an autoexec.cfg in steamapps/common/Alien Swarm/swarm/cfg/ then just make one and ensure that the file extension is .cfg and not .cfg.txt. If you are using Windows, you will need to enable showing file extensions to check this.


Below are some useful commands. You can bind these commands to a key or mouse button by using the bind command.

Miscellaneous trivia about the default Jacob's Rest campaign.

Cargo Elevator
In Cargo Elevator, the movement of the elevator is accomplished by moving the elevator shaft instead of the elevator. Presumably, this is to avoid physics issues that crop up when entities are moving around on top of moving map geometry.

Killing the aliens that are visibly crawling up the elevator shaft does not meaningfully effect the number of aliens that drop down onto the elevator. You are far better off just shooting the aliens that drop down.

Alien Swarm predates the Steam Workshop by two years, and given Valves love to abandon games, Alien Swarm never received workshop support.

Custom content is installed through .VPK files placed in the addons folder at steamapps/common/Alien Swarm/swarm/addons.

Installed addons are enabled by default, but can be disabled in-game by going into Options, Addons. Alien Swarm must be restarted when an addon is installed, disabled, or enabled.

Custom campaigns and mods can be found on ModDB, GameBanana[gamebanana.com], or swarmaddons[sites.google.com].

When installing an addon, ensure that only .VPK files are placed into the addons folder. Alien Swarm only recognises .VPK files as addons. If you have downloaded a .7Z or ZIP archive, ensure that you extract the .VPK from the archive, and then place the VPK file into the addons folder.

Note: Mods or campaigns that make mention of Reactive Drop may not work in Alien Swarm. Reactive Drop is a separate game that is based on Alien Swarm.

To help make playing Alien Swarm's custom campaigns easier I've curated a small set of high quality custom maps and uploaded them to MEGA. You can pick & choose or just download them all and put them in your addons folder. Click here to view the addons.[mega.nz]

Below are some high quality custom campaigns I'd recommend checking out. Do note that many customs are not balanced for solo play. You'll want at least one other player to join you.

• Midnight Harvest (ModDB) (download)
  
• Paranoia (ModDB) (download)
  
• Tears for Tarnor (ModDB) (download)

• Delusion (ModDB) (download)
  
• Orion Threat (ModDB) (download)

• Juno Outpost (ModDB) (download)
  
• Brook - download[mega.nz]
  
• Tech Abuse - download[mega.nz]

Alien Swarm is not a dead game but there are certainly times when very few if any players are visibly online. Checking SteamDB[steamdb.info] can be an indicator of when at least some players are online, however it isn't a good indicator of how many lobbies are accepting new players.

You'll generally see the most activity at 5 PM (18:00 UTC, 1 PM CDT) and later but random groups of players can come online earlier than that as well. Weekends tend to be more active than workdays.

You can use worldtimebuddy[www.worldtimebuddy.com] to easily see what 5 PM UTC is in your local timezone.

Some people have had luck with making threads asking for other players on the Steam Discussions however you may have to wait a few hours for a reply. You can also pop in my Steam Group Chat to see if anyone is playing or ask if anyone wants to play for a bit.