When selecting characters, consider what your team needs to tackle the particular mission. If you don't know what to expect, prepare for anything. If you can afford the space, a turret, a tesla cannon or a flamer, an ammo satchel and a medigun are a solid selection for your secondary slot. Not all custom maps advertise the fact that a tech may be essential for completing the level, so it's a good idea to have one when in doubt. Further on you'll find a list of suggestions for your primary weapon.
They get the best toys. Nearby marines will be so jealous of how nice their toys are, they will perform better in hopes of one day becoming officers themselves.
Sarge A hardened leader, his proximity will inspire nearby marines to magically amplify their weapons’ damage output and shrug off some damage. Hardy and capable with various weapons, including the officer-specific Vindicator, as well as explosives.
Jaeger Less of a leader, but does more damage with the Vindicator than Sarge, though his performance with other weapons is mediocre. A master of explosives and no stranger to melee combat.
Special weapons specialists
Touting autoguns and miniguns, they make swarm die of lead poisoning.
Wildcat The faster character in the game, she deals the most damage with conventional weapons and reloads quickly. Her speed helps offset the speed penalty imposed by autoguns and miniguns. Her bullets have a 40% chance to pierce the target and continue their flight.
Wolfe With a lot of health and a spectacular bonus to autogun damage, he is the very image of a “heavy weapons guy”. His performance with other weapons is less impressive than Wildcat’s, though still respectable, however his bullets pierce enemies 60% of the time.
Keeping the squad alive, they are indispensable for any team.
Faith Faith is the second faster character in the game, and is an excellent medic. She gets more charges for medical equipment and cures infestation faster.
Bastille Bastille is a combat medic, he gets a respectable boost to conventional weapon damage and reload speed; his presence inspires the entire team to get more juiced up on adrenaline.
They hack doors and computers. A fair number of missions cannot even be started without one. All marines will benefit from their scanning ability, which detects nearby swarm and displays their position on the minimap.
Crash He reloads faster than any other marine, does good damage with conventional weapons, and is decent with explosives.
Vegas He packs a mean melee punch and has a lot of health; his skill with sentries and the hand welder is second to none.
Make sure the team knows how they should move and aren't shy of communicating freely. Microphones are great, but if you don't have one, you can use the quick menu (Default key: Z) to make your character say a few lines. "Binds" are also a great way to communicate, allowing you to send a text message, have your character say one of their lines and/or display an emote. Making binds will be discussed in the last chapter of this guide. Characters will also call out spotted bugs on their own, make sure to listen for their comments. You can give "Follow me" and "Stop" commands by hitting V and X, respectively. You can ask your teammates to use their secondary piece of equipment by pressing the number key associated with their position in your roster, shown at the bottom of the screen (e.g. if you want the third marine to deploy their ammo satchel, hit 3).
If you have 3 or 4 marines, it is a good idea to establish a formation. Covering both the front and the rear is important, as is the ability to control and kill enemies approaching from both directions. A square formation is ideal for 4 marines in most situations, with a crowd control marine and a damage dealer walking shoulder to shoulder. If you only have 3 marines, a triangle formation, with the crowd control marine filling in where necessary, is logical. If you are required to defend a position, designate firing zones to prevent being rushed from behind by a swarm while everybody is distracted by pumping lead into a shieldbug.
Sticking to a chosen formation will help you avoid friendly fire and reduce the possibility of a drone slipping in and wreaking havoc on your team. Forward-facing marines must have room to retreat when faced with a large swarm to avoid breaking rank. Use freeze grenades and other crowd control offhand equipment to deal with huge swarms. If several marines are carrying such equipment, it can be a good idea to agree on the order of usage, to prevent wasting items by using them simultaneously. Agreeing on one marine deploying all of their ammo satchels before the others start deploying theirs is also a good idea, as it will allow you to have a full set of ammo satchels if one of you dies or you need to pick up extra equipment.
Using the shift key to slow down (and spin up the barrel, if you have a minigun) can be a good tactic to avoid friendly fire, and so is not moving erratically - if you are constantly darting in and out of your teammate's field of fire, then their ability to engage the swarm (or, worse, your ability to keep breathing) will be severely diminished, especially if you are playing with hardcore friendly fire enabled.
(Prototype) Assault Rifle A weapon overlooked by most experienced players due to being the first gun in the game, it is nevertheless a very capable firearm. Doing more damage per round than the autogun, it requires half as much ammo to top off from an ammo satchel. More importantly, it has a grenade launcher with 5 grenades (Stun grenades for the prototype rifle, explosive grenades for the regular rifle), which can save you from a tight spot, especially the stun grenades, as they deal almost no damage to teammates. Best suited for characters who have a damage bonus (Bastille, Crash, Wildcat, Sarge). The prototype's rifle autoaim can be useful for killing offscreen swarm (Watch for the laser twitch) and detecting swarm in dark environments.
Tesla cannon Previously the most powerful gun in the game, it has long since been nerfed. Still, it remains useful as a secondary weapon due to its amazing stun capabilities and utter lack of friendly fire damage. Shield bugs in particular become extremely easy to dispatch after being hit even with even the shortest tesla cannon zap. Make sure to use small consecutive zaps, rather than continuous fire, to conserve its limited ammo. Zap infested teammates to slow down infestation rate.
Vindicator This officer-only gun is a paragon of destruction. Holding 14 shells, it can stop a swarm charge on all but the highest difficulties and still have some shots left before having to be reloaded. The 5 incendiary grenades it holds for secondary fire can be a godsend for when you don't have a flamer to burn some biomass or a cluster of eggs. The grenades are on a timer, but will explode immediately if they hit a swarm before coming to a stop. PROTIP: if you are going to die due to parasite infestation, shoot a grenade or two at your feet, and the newly-hatched parasites will meet a timely end. It takes a pro to kill the parasites that killed you.
Autogun and minigun These bad boys can only be handled by the burliest and/or fiercest members of the team, i.e. the special weapons specialists. What they lack in features and damage per shot, they make up for in their ability to pump out a lot of bullets in little time. The autogun has autoaim and does not require any spin-up before firing, unlike the minigun. The minigun, however, deals a lot more damage, making it more useful at higher difficulties. Special autogun ammo crates are scattered throughout levels, so make sure to remember where they are to avoid having to explain why you left the team with no ammo. Having these weapons equipped will cause you to move 20% slower, but switching to another weapon will let you move at full speed.
Twin pistols Semi-automatic sidearms that can fire as fast as you can click. They can be fired and reloaded while running, which can be useful. Make sure to resist the temptation to start rushing when wielding those.
PDWs Personal defense weapons are a pair of SMGs that deal the most damage per second of all firearms in the game. To compensate, they chew through ammo at an incredible rate. Truly devastating in the hands of a character with a respectable damage bonus.
Pump-action shotgun Does significant damage at an acceptable fire rate, but only holds 4 shells, resulting in frequent reloads. Does more damage than the Vindicator. Requires a lot of ammo to get through an average mission. High spread. Good as a secondary weapons or a primary if your squad can afford the ammo consumption.
Sniper and rail rifles These deal a lot of damage per shot, but are limited by their firing speed. The sniper rifle is equipped with a scope that lights up swarm in green, but obscures an area around your target; the scope is activated by secondary fire. The rail rifle only holds 1 round, forcing you to reload after each shot; if you choose to use it, make sure you are adept at getting quick reloads with it, or that your character has a sizeable reload speed bonus (Crash, Bastille, Wildcat). The sniper rifle is able to pierce doors, allowing you to thin out the herd before engaging it. Sniper rounds penetrate 1 enemy, allowing you to hit 2 targets at once. Rail rifle rounds travel until they hit a wall, damaging all the swarm in their path.
Flamer A powerful crowd control weapon in skilled hands, or a team kill disaster waiting to happen. Its secondary fire is a fire extinguisher, use it if you've made an oopsie, or if you're faced with a wall of flame. Use short puffs to conserve fuel and avoid settings your teammates ablaze; its damage to team members (And, indeed, the swarm) is so little that it is perfectly fine to send a few puffs through a teammates if they are being swarmed, provided you don't overdo it. It is, however, not a kill weapon, so avoid bringing too many of these, or you will simply be crushed by a swarm of burning drones. Be wary of using it too liberally if you have hardcore friendly fire enabled, as it will be more prone to set teammates on fire.
Chainsaw The chainsaw is wonderful for opening doors and breaking rocks in a hurry, if your character has a good melee damage bonus (Vegas, Jaeger). When using it, avoid moving away from a nearby drone - it will lunge and hit you, instead go toward the enemy to kill it. Try to avoid using it as primary weapon, as doing so will cause you to constantly run into your teammates' lines of fire, resulting in decreased squad performances due to them having to afford you special attention. Chainsawing a tesla-stunned shieldbug or mortarbug is the most efficient way to deal with these enemies. If you are short a person, a proficient chainsawer (likely playing Vegas) can hold the front or back sufficiently - it works best solo or backed by a tesla cannon.
Grenade launcher The last weapon unlocked in the game, the grenade launcher is a weapon of massive devastations, which it will visit indiscriminately upon friend and foe. Very useful against small and medium-sized aliens, killing most in 1 shot. Grenades have a large area of effect, so care should be taken when attacking enemies close to you or your teammates. With some practice you may be able to dispatch nearby enemies by shooting grenades to the side so that the enemy is in the blast radius, but you aren't. Very ammo-efficient, refilling its 3 clips with just 20% of an ammo satchel. Not a team weapon and incredibly dangerous in untrained hands, most likely should be avoided if you want the satisfaction of completing a mission as a team - it's not a lot of fun to run through a mission if somebody has killed all the aliens on their own.
Sentries The sentries are useful for defending an area. It is a good idea to deploy one before starting a hack of opening an unrealistically slow door. The regular and freeze sentries are the most efficient, while the flame sentry is merely adequate. The grenade sentry is a disaster, avoid it at all costs. Sentries don't care about friendly fire and normally don't do any damage to friendlies (Flame and explosive sentry excluded, these ♥♥♥♥♥♥♥s will kill you given the slightest opportunity), but if you have hardcore friendly fire enabled, they become a significant menace if you stroll into their line of fire.
Heal beacon Heals teammates within a small radius when deployed. Requires injured marines to remain close to it, which can be dangerous and inconvenient. Requires a full charge to heal the smallest scrape. Inferior in almost every way to the medigun. Its redeeming qualities are that multiple beacons can be deployed to increase healing speed, and that the medic is free to use their weapon after deploying it.
Medical gun Can be used on the move, though it slows down the medic to walk speed. Healing continues for a short time after the gun stops "firing", avoid healing a marine to full health, instead allowing the heal-over-time effect to bring them to top health.
Hand welder Useful for welding and unwelding doors, which can give you a tactical advantage or allow access to a weapon cache. Using it means you aren't using a different item, so make sure to stay close to your teammates and to have a means of crowd control. Proximity of a tech specialist will give a sizeable boost to welding speed.
Freeze grenades These come at a pack of 5, and allow you to freeze a large number of swarm anywhere on the screen. Extremely useful for bailing out a swarmed teammate or yourself. Frozen swarm are more susceptible to melee damage, including the chainsaw. Great for priming a shieldbug for a kill, especially if you don’t have a tesla cannon.
Electric Charge Armor 3 charges, each lasting 12 seconds. Stuns nearby swarm and swarm that hit you. The only way to heal a parasite infestation without a nearby medic, though it takes time, during which you will still receive sizeable damage. A parasite will be instantly killed if it attempts to infest a marine while the item is active. The ability to remove infestation makes it highly useful.
Tesla coil Come at a pack of 3, these will zap nearby swarm, debilitating them. They will run out of juice eventually, so make sure to dispatch the zapped swarm quickly to increase the number of affected aliens. Can be used to stun a shieldbug for a prolonged period of time, though it is a bit wasteful.
Hornet barrage 3 charges of 8-missile salvos. New player's freeze grenades, these are available fairly early on and kill a good number of swarm around you. Useful when you are getting swarmed, or for taking out a bunch of parasites.
Damage amplifier Comes in a pack of 5. Useful when defending an area. Doubles the damage of conventional weapons. Useful for early levels and for dealing with ridiculously huge swamrs. Having to remain in its limited radius can be dangerous, however. Miniguns and PDWs will annihilate aliens while buffed by a damage amplifier.
Trip mines 12 a pack. Drops 1-3 mines, depending on your character's Explosives bonus. Can be thrown onto the floor or walls. Useful for defending an area.
Proximity incendiary mines 5 a pack, officer-only. Creates a wide wall of flame perpendicular to the direction the marine was facing when deploying it. Sarge’s firewall lasts 20 seconds, Jaeger’s - 30 seconds. Destroys drones, parasites and harvester spawn, severely damages bigger aliens. Able to kill a shieldbug on Brutal if you can keep it on the fire mine. Great for defending against waves of enemies. When blocking a tight passage, like a door, consider dropping the mine parallel to the passage, so that aliens have to pass through more fire to get through.
Smartbomb Basically the 3 charges of a hornet barrage chained together. Single-use item. Mostly overkill. Used primarily when you want to pick up a blink pack or assault jets that are close to the beginning of the level.
Personal healing kit Great until you unlock any other worthwhile offhand item. Sometimes these will be scattered in a level, allowing you to conserve medigun charges.
Adrenaline 3 charges a pack. Slows down time for 10 seconds (16 if you have Bastille in the squad). Useful for high-tension situations and hacking. Produces an excruciatingly slow death cinematic if a marine is killed while adrenaline is in effect.
Power fist Useful for killing the stray drone that managed to get close to you on higher difficulties. Mostly useless if your team is good.
Blink pack Available only as a pickup on Timor Station, it is a rechargeable personal teleporter. Stuns enemies around your points of departure and arrival, which can be useful for getting out a tight spot or stunning a shieldbug.
Assault jets Rocket boots. 5 charges. Useful for getting around fast. Landing on top of swarm damages and pushes them back, though the radius is limited, so if your landing area has many enemies you may get chewed upon.
Combat flares 15 a pack. Provide autoaim against swarm illuminated by their glow. Mostly useless. Provide illumination in pitch-black environments, could be useful on some custom maps.
Flashlight and nightvision goggles Junk. Might be useful on custom maps that feature a lot of dark environments.
Heavy armor Decreases received damage by 20%. Passive. Useless.
Ideally, a team should have 4 people: 1 medic, 1 tech (if required) and 2 damage dealers (special weapons or officers). If a mission doesn’t require a tech, you can swap him for an additional damage dealer or a medic if you are constantly running out of medgun. If not specified, offhand items should usually be crowd control (freeze grenades, hornet barrage) or electric armor if the map is parasite-rich. Having more than 1 Tesla cannon and 1 Flamer on your team is not advised. Depending on mission length and how ammo-hungry your weapons are, you may want to have 1-3 ammo satchels (if you’re packing rifles and vindicators, 1 or 2 is enough, if you have a shotgun and PDWs then 3 will likely be required).
Jaeger Weapon: Vindicator Secondary: Ammo satchel Offhand: Incendiary proximity mines
Sarge Weapon: Vindicator, shotgun, assault rifle Secondary: Ammo satchel
You can customize the key that triggers a bind and the text that it displays, but try to keep it concise - nobody wants to read an essay on the virtues of staying alive while there is a horde coming.
Change the bind X keys to whatever suits you best. Save it as "autoexec.cfg" in your Alien Swarm CFG folder (most likely C:\Program Files (x86)\Steam\SteamApps\common\alien swarm\swarm\cfg). Next time you start up AS a couple of things will have changed, your UI will be more informative, and you will be able to use the binds you've chosen to communicate quickly.
You can also do some cool stuff like rebinding your reload key to, for example, your mouse's extra button (assuming it has one) or a different key, because it's very hard to reload and move right simultenously, as so
bind "MOUSE4" "+reload"
It has come to my attention that some otherwise intermediate players have no idea how to hack computers. The hacking minigame consists of a number of columns moving vertically. Each column is independent of other columns and can move either up or down and has only one 1 symbol on it. The object is to line up the ones so that they are aligned horizontally and all moving in the same direction. In order to do that, you need to first select which columns you will be syncronizing other columns to, let's call it a base column. Most of the time, at least a few columns will already be matched, if that's the case you should match other columns to them to save time, otherwise start with whichever one you like. To the right you see an example of how the hacking minigame looks - note the 3 leftmost columns have already been aligned.
To match columns, look at a column adjacent to your base column (it doesn't have to be adjacent, but it's easier that way) and note which way it moves - if it moves in the same direction as your base column, click it once to revert its direction, then click once again when the ones line up; if it moves in the opposite direction to your base column, simply click on it when the ones line up on their own. Repeat the process for the rest of the unaligned columns to win the minigame.
A video demonstracting a simple hack. Note that you don't need to click on the arrows to change a column's direction, anywhere on the column will do.
Another type of hack in Alien Swarm is a bypass, it is much more straightforward and common than computer hacking explained above. The object is to get the blue signal from the left side of the maze to the right side of the maze by rotating segments to create a path between them. Click on a segments to rotate it.
In rare cases, solving a bypass maze will not result in the line lining up properly with the maze terminator - this is not a bug, there is a valid path through the maze, you just got lost along the way. If that happens. go back and look for segments that have more than 1 valid possible position to get back on track.