The Boomer

"They've been calling those Boomers. For obvious reasons."

"Boomer, don't let it puke on you."

The Boomer is an extremely bloated Special Infected.

Its mutation has caused it to produce immense quantities of bile which it attempts to vomit on the Survivors, temporarily blinding them and summoning a small Horde. Though fragile and slow, the Boomers can be dangerous to a Survivor team whose health or combat abilities are compromised.

The Boomer's role in Left 4 Dead and Left 4 Dead 2 is to slow down, blind and sow general confusion among Survivors, giving the hordes of Infected of any species openings to mount attacks with higher probabilities than normal to achieve damaging results. The known presence of a Boomer may also cause Survivors to spread out a little (to avoid being coated in bile) and this too works to the advantage of Special Infected such as Smokers or Jockeys when mounting a co-ordinated attack.

The Boomer is voiced by Fred Tatasciore.

Appearance

In both games, the Boomer has short black hair and wears a navy blue shirt and brown pants, both stained with sweat and puke and stretched to breaking point around the Boomer's enormous gut. When idle, the Boomer makes loud burping and gurgling noises which change to loud groans when it sees a Survivor.

If a Boomer encounters a Survivor team at distance and out of range of its projectile vomited bile, it will waddle off into cover and attempt to stalk the team. At closer distances, a Boomer will move into an ambush position (e.g. behind a pillar or vehicle) until the Survivors get within range. However its unrepressed groans and large body make it relatively easy for an experienced team to fix its location and neutralise the threat without harm to themselves.

Extent of Mutations

The Boomer has undergone extreme external and internal mutations by some adverse reaction to the Infection. The most notable observation of the Boomer is its extremely bloated belly, most likely caused by its stomach (and possibly most, if not all of its gastrointestinal system) being hijacked by the infection to overproduce bile in massive amounts. The sheer tension on its skin and organs has resulted in a breakdown of the epidermal and dermal layers, causing the skin to become thin and fragile. In some places the skin has even ruptured, exposing some of the bile-filled internal organs. This enormous buildup of internal pressure makes the Boomer quite vulnerable to any outside agitation, as even the slightest gunshot wound or melee shove will result in the Boomer violently exploding, sending blood and bile everywhere - hence its name. Even so, the Boomer can autonomously engage in strenuous self-directed physical activities (e.g. jumping down from a height) without injury.

Other physical mutations observed include massive boil-like growths that appeared upon its skin and face. Whether this is due to overproduction of bile is unknown. Similar to the other Special Infected, it is not distracted by high frequency noises such as pipe bombs or car alarms going off.

The Boomer's bile has a unique chemical binding effect with infected and/or non-infected flesh which produces an extracellular stimulus. This chemical stimulus induces a pheromone-like attraction from nearby common infected which causes them to swarm and attack the bile-saturated source. The exact nature as to why this induces a negative response is unknown but the response is non-discriminatory between infected and non-infected flesh (i.e. using a Boomer bile vial on the Tank triggers the same violent response against the Tank). It should be noted that typically common infected have been known to exhibit an extremely basic form of logic (hence their ability to recognize non-infected). The bile-flesh response seems to trump this logic, which could mean that the stimulus is extremely intoxicating for the common infected.

Left 4 Dead 2

Boomer 2 — The new Boomer in *Left 4 Dead 2*.

Boomette 2 — The Female Boomer in *Left 4 Dead 2*.

As with all the original Special Infected, the Boomer reappears in Left 4 Dead 2 and has received a slight change of appearance. Its skin tone is more fleshy, it has shorter hair, and has a few more boils. Though when compared to his Left 4 Dead counterpart, he seems more wrinkly and "deflated", and his skin seems to be breaking out in several spots. The greatest change in the Boomer's appearance, however, is the addition of a female counterpart.

CEDA has shown some interest in the Boomer, hoping to utilize its unique abilities to their gain. A wall chart detailing its appearance and abilities appears early on in Dead Center, and Infected Hazmat-clad CEDA operatives can be found carrying vials of treated Boomer bile.

Female Boomer

The Female Boomer (or "Boomette") is seen wearing a dark blue or black tank top and blue jean shorts, drenched in bile. Unlike the male Boomer, she doesn't have boils or growths. Instead, her flabby flesh shows signs of fungus growth, and perhaps highly Infected forms of tinea around her shins. The skin on her hands and wrists appears blackened from necrosis, similar to gangrene.

Her eyelids and the skin in the area around her eyes are also black. Her teeth seem to be heavily misshapen and worn down, either meaning she either lacked proper dental hygiene before she became Infected, or her constant puking has broken down the enamel in her teeth (or possibly a combination of both). She makes higher-pitched gurgling noises as compared to the male Boomer, and sounds more pig-like.

In terms of gameplay, she functions exactly the same as the male Boomer. In Versus you will be randomly picked by male or female, if you are the female, the hands will remain the same as the male even though the female's hands are dark, black and don't have boils.

Abilities

The Boomer's primary attack is to launch a stream of vomit which can hit multiple Survivors that are close to it. If it is killed, it will explode, causing Survivors (and Infected) close to it to stagger and spraying Survivors with bile. Survivors hit by Boomer bile will have their vision obscured (losing outlines of their teammates as well) and will instantly attract a Horde to attack them, as well as any individual Common Infected who happen to be in the area. They will glow yellow to teammates and purple to the Infected.

Multiple Survivors hit by Boomer bile will not each attract a Horde to them; the one Horde will instead attack all of them. This is also true of Survivors who are covered in bile by the Boomer's death after the Boomer has used its vomit attack; a second Horde will not be attracted until the effect has worn off upon the Survivor's first hit, and until the Boomer itself attacks again. The Boomer may vomit on incapacitated Survivors and on those who have been pinned by other Infected. Boomer bile, at least that issuing from the Boomer itself, has no effect upon other Infected. The Boomer may also claw the Survivors to do 2 points of damage on Normal.

Attacks

Left 4 Dead

Types	Weapon	Damage	Properties	Cooldown
Primary Attack	Bile	N/A	Will cover hit Survivors in bile, blinding them and attracting a Horde (also spawns a certain amount of Common Infected, about 20). You can also get additional range with this when aiming slightly up.	Between pukes: 30 sec. (Plus additional 2 sec for the puke. Cooldown starts after you stopped puking.) Blindness of Survivors: 15 sec.
Secondary Attack	Claw	4	Hitting Survivors who are currently occupied with something (e.x. helping up other Survivors) will get their action canceled.	1 attack per second. You can also attack while stumbling, even if you are currently not in the ego-perspective.
Special Attack	Bile Explosion	N/A	If the Boomer dies, he releases a bile explosion, covering every Survivor around him in bile and shoving everyone back (this includes teammates and will result in stumbling for 1 second).	N/A

Left 4 Dead 2

Types	Weapon	Damage	Properties	Cooldown
Primary Attack	Bile	N/A	Will cover hit Survivors in bile, blinding them and attracting a Horde (also spawns a certain amount of Common Infected, about 20). You can also get additional range with this when aiming slightly up.	Between pukes: 30 seconds (plus additional 2 sec for the puke. Cooldown starts after you stopped puking.) Blindness of Survivors: 15 sec.
Secondary Attack	Claw	4, 20 (Expert)	Hitting Survivors who are currently occupied with something (e.x. helping up other Survivors) will get their action canceled. Filling in gas tanks counts as occupation.	1 attack per second. You can also attack while stumbling, even if you are currently not in the ego-perspective
Special Attack	Bile Explosion	N/A	If the Boomer dies, he/she releases a Bile Explosion, covering every Survivor around him/her in bile and shoving everyone back (this includes teammates and will result in stumbling for 3 seconds).	N/A

Note: Information still needed for some areas.

Tactics

Survivors

General:

Listen for the heavy breathing, gagging, moaning, groaning, and burping sounds.
If Boomer is trying to hide, find its large belly and then give it a little poke, go on!
If a Boomer is taking cover behind thin walls, use a Hunting rifle (or weapon with high penetrate abilities) to shoot through walls and kill him/her.
If a Boomer is nearby and has not vomited on anyone, shove him back to a safe distance and shoot him.
- You can also try to run up to him and shove him to delay his ability to vomit. Even if he attempts to vomit, a shove that hits quick enough can interrupt the attack.
Turning the subtitles on allows players to read the Boomer's noises if it is near. This is extremely useful in noisy situations such as the rainstorms during the latter half of Hard Rain or during finales.
- Game captions help when dealing with Boomers, as with all other Special Infected. When the captions give the "Boomer Rage!", this means it has spotted you. When it shows "Boomer Warning!", this means the Boomer is within puking distance of you. When it says "Boomer Falls", this means it has fallen from a distance.
Keep an eye out for defensive positions. That way, you'll be ready if the Boomer blinds you.
Avoid being too bunched up with the other Survivors. There's no sense in all survivors getting puked on at once.
On Expert, finding and killing the Boomer before it can vomit or explode is incredibly crucial, as the Boomer bile attracts the Horde, which, on Expert difficulty, is much more excruciating in terms of gameplay checkpoints than any other.
Boomers will often claw Survivors they have vomited on, dealing even more damage. Survivors should be cautious, especially on Expert, because it will do 20 damage per hit.
The Boomer is probably one of the most difficult Infected to deal with. This is mainly due to the Boomer's ambushing capabilities. They will usually hide around corners or drop down from a high rooftop to "pop" on the Survivors.
Take advantage of the fact that Boomers will explode if any part of their body is attacked. Due to their bulk, their arms are often exposed around corners. Just a few rifle blasts could mean the difference between being drenched in puke and escaping unharmed.
Never use melee weapons against a Boomer if you are shoving it away to shoot it from a farther range.
- When the Survivors have not retrieved any primary weapons yet, have at least one teammate arm himself/herself with a pistol that he/she can dispatch a Boomer safely.
When a Boomer is near, stay away from ledges. The recoil from the explosion can push players off. On the up side - the recoil will also stun Infected who are located near the Boomer for a moment.
Like other Special Infected, watch out for Boomers when fighting Tanks. You really don't want another annoyance when a big threat is already present. Furthermore, on Expert difficulty, a mob of Common Infected can be as dangerous as the Tank himself.
- You might be able to use the boomer to stumble the Tank if they are close enough together, giving yourself more time to damage the Tank.
If a teammate is down and a hoard is making it difficult to help them up, and no Pipe Bombs or Bile Bombs are available for use, consider allowing yourself to be covered in bile: the infected will mostly focus on you and not your downed teammate, and you can insure that no other teammates will be boomed.
- If you and a downed or heavily injured teammate are both covered in bile, take a more forward position to attract the aggression of the infected, keeping them away from your vulnerable teammate.
If you are bogged down by infected, consider using a Molotov to burn all of the infected surrounding you. Throw it at your feet and run to escape the fire; the infected will instantly die unless they are fireproof uncommon infected.

Before bile vomit or Boomer death explosion:

If the Boomer is too close, it's a good idea to hit it with your melee attack (which will push it back to some degree), then back away to a safe distance before shooting, or there is a risk of getting covered in bile.

Survivor's view after being vomited on by a Boomer.
- Caution: It is only possible to safely push a Boomer back about three to four times, as doing it much more will cause it to burst.
Only if the Boomer is sufficiently far away from all Survivors should players shoot it.
- If a survivor has already been coated in bile, it is much less of a problem for them to get caught by the explosion of a Boomer, as they will not be blinded any longer than otherwise and no new infected will spawn. However, they will still be stumbled, giving infected extra opportunity to attack.
  - Infected near the survivor will probably be stumbled by the explosion as well, however, so even the knockback may not be a significant problem.
Hiding behind something or running away when a Boomer vomits makes it harmless for some time and may even force it to rush in and try to melee.
If the Boomer has vomited on someone and is still close to the bile-covered Survivor, shooting the Boomer and (again) covering the Survivor in bile will not attract an additional Horde.
When a Boomer is killed, remember that this will stumble anyone, friend or foe. The explosion will also send items that have been dropped (non-static, or have been moved from their original spot) flying away a fair distance. It will also set off car alarms. Don't kill a Boomer if it is near a Witch (it stumbles her and then she will attack you), near alarmed cars, or near crucial items that you have moved there.

After being vomited on:

Know that a massive Horde will immediately descend upon you (and any others who have been slimed).
If teammates are nearby, do not shoot. It is hard to see and friendly fire is more likely. You need to:
- Run to a defensive position (corners and doorways are particularly good). If confident that your teammates can deal with the horde and help you up, try falling off a ledge so that you'll hang. While this can be very risky, most of the charging Horde will run off the ledge (often to their deaths) and deal no damage to you. Elevated positions are also helpful, delaying the infected while they climb towards you.
- Crouch! Other Survivors will be able to shoot over you safely if you do so.
- Use melee continuously to survive the incoming Horde, or if you have a melee weapon, slash them if they get to you.
- Follow the sound of players being attacked by other special infected. If everyone has been boomed, nobody can see each other, so nobody knows if their teammate in the next room has been pounced.
Throw a Pipe Bomb to distract the infected temporarily, giving you time to get to a defensive position, regroup, reload, and prepare, as well as thinning the hoard.
- Do not throw a Bile Bomb however, the infected will prioritize you over the bile.

Helping a slimed Survivor:

Stay close to the stricken Survivor; if you get attacked, they will notice more easily, and when they get attacked you can assist them.
Help melee the Horde back or shoot if the blinded Survivor stays safely crouched.
Help the stricken player safely reach a corner or high ground to protect him/her from the Horde.
Throw a pipe bomb to distract the Horde; however, if you throw a bile bomb, it will go to waste, as the Survivors covered in bile are primary targets for the Common Infected.
Watch out for your teammate wildly swinging a melee weapon. You don't want to be hit accidentally.

Survivor Bots' reaction to Boomer:

Bots will always try to shove Boomers away if they are too close. They will not attempt to attack the Boomer with any melee weapons, if holding any.
Bots will not shoot Boomers if they are too close.
Bots can shoot like normal even when they are slimed but only in Left 4 Dead. In Left 4 Dead 2. If they got vomited on, they will start to shove at 'random' directions or run and shove, but semi-rarely shoot.
If all human players are outside the vomit and explosion range, let Bots take care of Boomers by themselves. They are better at handling Boomers' exploding range.

Infected

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"The Boomer was designed to distract, injure and frustrate the Survivors with several surprise waves of Infected hordes, as well as break the "shoot everything that moves" mentality. While the other Infected are attackers alone, the Boomer plays a highly valuable supporting role."

While playing as the Boomer, one must keep in mind that one is playing a support class. He/She serves as the initiator of ambushes, the one who starts panic. While playing as the Boomer, avoid charging in with ravenous zombie hordes to inflict underwhelming damage with melee. Instead, puke on Survivors from unseen locations, wait for teammates to start an ambush, and jump in at hectic moments to explode and cause increased confusion.

Boomerhide — A Boomer hides in attempt to surprise the Survivors in the early stages of the game's development.

Instead of engaging survivors directly, wait for them to come to you. Sometimes it is more effective to wait around a corner and let them come into puking range. This is because there is a delay between a Boomer stopping its movement and puking. Play it safe and let them come.
- Players may also accidentally react and shoot you without backing away, covering them in bile.
The Boomer makes very distinctive sounds, making it easy to determine when and often where a Boomer has spawned. To reduce the chance of being killed before getting a chance to attack, spawn immediately before vomiting, somewhere close to where all of the survivors are grouped together, preferably while the survivors are distracted with other infected or actions (such as healing).
The Boomer's explosion can send loose items (such as a dropped Gas Can or supplies dropped by a dead teammate) flying, making it difficult for survivors to locate and retrieve the important supplies.
- This can be significantly more effective in Scavenge mode, The Atrium, and The Port where it is likely that the survivors will be tossing cans as they move, allowing an exploding Boomer to send the gas cans flying away and force the survivors to go out of their way to retrieve the cans. While players cannot control precisely where the gas cans will fly off to, it is possible for a can to be launched to a place where the survivors can't retrieve it, such as off of a rooftop (most notable in the No Mercy Rooftop scavenge map). This will force the survivors to try and destroy the can so it will respawn, giving the infected team more time to pounce on the survivors.
Once a Boomer has vomited on the Survivors, whether or not it has actually hit anyone, there are two options: use the kamikaze method, or run, hide, and recover.
- The most basic kamikaze method a Boomer can use involves walking up to the Survivors after vomiting on them, and clawing them. This will not only cause a bit more damage, but will entice panicked Survivors to shoot the Boomer at close range (note that a Survivor whose vision is already impaired may be more likely to shoot if clawed). If the Boomer is killed close enough, its bile explosion will cover any missed targets, re-cover victims already covered in bile, and cause the Survivors to stumble for a brief period. The downside is that this leaves the Infected a man short and, in Left 4 Dead 2, there is no guarantee that a Boomer will reappear next wave. Additionally, alert Survivors will easily melee shove the Boomer back to a safe distance and dispose of it. Exploding near a Special Infected while they are attacking an already incapacitated Survivor releases the attacking Special Infected, allowing them to escape and attack again later. This is particularly useful with Chargers and Hunters, because they can attack almost immediately after being knocked free.
  - A variation to the kamikaze method is to stand in an area above where the Survivors will pass later. Jump down into the middle of the group and get killed. The resulting bile attracts the horde and makes it easier for other Infected players to deal damage due to the confusion caused. A Boomer can also light itself on fire, and then explode all over them before they realize it was even there. This is not recommended for new players as the survivors might take a longer time than anticipated to reach the area player, resulting in death.
  - The final trick is to stand next to an alarmed car facing the Survivors. They will most likely open fire, killing the player but also hitting the car and summoning a horde. Do note that Survivors need to be close enough to a car to trigger the alarm; bullets fired from far away won't do.
    - This method can be applied to the Witch as well. Once the Witch has been startled, the Infected team should attack to create even more chaos and to prevent the Witch from being killed before incapacitating someone.
- Alternatively, the Boomer can flee after puking, let their bile recharge, and puke again later. This allows the Boomer to recharge its bile while the Survivors are currently dealing with the panic you caused. Some Hordes last longer than the time it takes the bile to recharge, allowing you to pull off the combos in quick succession and can be used to buy your teammates more time. However, since you are still a part of the field, you will be making a lot a noise, which will keep Survivors aware of your presence. To counteract this, hide in locations they wouldn't expect to see a Boomer or in the Infected-only areas. If you can get enough distance between you and the Survivors, you can get the game to prompt you with the "Press E/X to move closer to the Survivors" message, which will bring you right back to them in Ghost Mode, allowing you to have the perks of respawning without having to die.
  - However, Boomer bile has the longest recharge of any Special Infected ability, meaning that the infected will be short one person for the duration of the bile recharge period. It is actually faster to kill oneself and respawn than it is to wait for the bile to recharge.
To generate additional Infected, you must either explode on a non-purple Survivor or wait until all Survivors are no longer surrounded by a purple aura and then strike again.
Another tactic that many experienced players use in gameplay is a maneuver called a Rocket Boomer, in which the player is in spawn mode and they climb to an elevated surface, then they run toward the edge at the survivors, and while in mid-air, they spawn and land in the center of the survivor players.
- Infected can accumulate significant speed while in spawn mode, and spawning mid-air allows players to maintain their momentum.
Work with other Special Infected to maximize damage and confusion during an attack. Boomed survivors will have difficulty killing SI that are attacking other survivors, and pinned survivors are vulnerable to attack from common infected. Additionally, Survivors that are carried away from their teammates will not be visible to boomed players, and if carried far enough will not be heard by teammates. An infected can attack until the bile wears off entirely before being discovered, inflicting massive damage and possibly resulting in the death of the survivor.
If a Boomer and Spitter are on the field at the same time, Infected teams can deal out a lot of damage to the Survivors who cluster close. The Boomer can first summon a wave of Infected on one or more players. Once the Common Infected surround a player, having the Spitter spit on them will magnify the damage dealt. Survivors will be held in place by the infected while taking increasingly high damage from the acid. Boomers can also jump in and explode, stumbling survivors into the spit. They will take even more damage due to their inability to leave the spit until their stumble wears off.
If the Tank spawns, having a Boomer slime even one Survivor is a huge bonus. The Tank will cause a lot of confusion, but if he is assisted by a wave of regular Infected, the Survivors can get overwhelmed quickly.
There is a delay between the activation of a bile attack and a Survivor being coated. If the Survivor kills or shoves the Boomer, the bile will disappear in mid-flight, leaving the Survivor clean.
While a Survivor is covered in bile, they cannot see the outlines of the other Survivors (or that of the Hunter, Charger, or Jockey after being pinned). While another Infected is attacking a straggler, take the opportunity to cover the other Survivors with bile. While this may cause the Horde to spread out, it is important to impair the other Survivors' vision so that it becomes more difficult for them to work together and to aim.
The Boomer should almost always attempt to cover an incapacitated Survivor with bile. If you can, try to vomit on downed Survivors so that the Horde attacks them. The infected will prevent them from being revived, and attacks from common infected will do a significant amount of damage to downed survivors (5x damage on Versus).
There is a maximum distance the vomit can go before disappearing into thin air. If from too high of a vantage point, the bile will never hit Survivors.
Don't hide right next to thin walls. Not only can Survivors shoot through most of them, but your ample mass may stick through (due to vector errors), giving them a free kill. The slime from the aftermath will, unfortunately, be unable to get through. Try to hide slightly off the wall to minimize cheap kills.
When the Boomer explodes, it knocks everyone back. This includes both Survivors and all Special Infected.
- This effect can be used to knock Survivors off of high ledges, resulting in their incapacitation. However, this can also affect infected, causing them to fall to their death.
- Exploding near a Special Infected while they are attacking a Survivor releases the attacking Special Infected, allowing them to escape and attack again later. This is particularly useful with Chargers and Hunters, because they can attack almost immediately after being knocked free.
If you have used your Boomer bile and missed a downed Survivor, sneak up on a single incapacitated Survivor and simply stand right next to him/her or start clawing them. The incapacitated Survivor cannot do anything about your presence other than shoot you, which will cause him/her to be covered in bile, resulting in swift death. You can also do the same to a pinned Survivor, and if any of his/her friends try to shoot the Hunter or Smoker pinning him/her, they may hit you, causing a similar result.

Boomer Tips and Tricks Gameplay

Here is a video with a lot of helpful information and tactics for the Boomer, courtesy of Criken2.

Achievements

See Main Article: Achievements

Survivors

	BLIND LUCK	(20G)
	You or another Survivor take no damage after being vomited on by a Boomer.

	CLEAN KILL	(10G)
	Shove a Boomer and then kill him without him splashing on anyone.

	STOMACH UPSET	(20G)
	All Survivors complete a campaign without being vomited on.

	OUTBREAK
	Catch a rare strain of Infection, then pass it on to someone else.

Infected

	BARF BAGGED	(20G)
	Cover four Survivors with Boomer bile at once.

Behind the Scenes

Boomer-vomit — Early version of the Boomer's bile.

In the Developer Commentary, it's mentioned that originally the Boomer's explosion simply caused damage to nearby players, and that the Horde-attracting abilities were assigned to the Screamer, another Special Infected that was cut from the final game. When the Screamer was dropped, the screams that formerly attracted the Horde were changed to the Boomer's bile. The Boomer's old explosion behavior can be seen in this video at 1:57:

When the Boomer's bile was first added to the game, it was red. It later was replaced by the green seen in the final version.

In the leaked Half Life 2 Beta files, this can be found: "A bloated, disgusting, fluid-spurting zombie created by a poison headcrab," commenting on the Poison Zombie. Take out the bit about the Headcrab, an alien creature which does not appear in Left 4 Dead, and this effectively describes the Boomer.

Notes

The Boomer was the first Special Infected ever conceived.

Boomer corpse copy — The Boomer corpse in the Intro Scene.

A very rare glitch will cause a Boomer to die without exploding. Bile will still cover any Survivors too close.
When the Boomer explodes or vomits, the bile does not appear on the ground. This fits in, because otherwise the Horde would always be attracted to the site of a Boomer death. As it stands, the Horde is only summoned when the bile comes into contact with a Survivor. It is possible that the Survivor's natural pheromones combined with the bile produces a scent that is strong enough to attract a horde of large size. Strangely, in Left 4 Dead 2, when a Bile bomb is thrown, it attracts a Horde, regardless of whether it hits an Infected or not. It may have been treated with pheromones by CEDA beforehand.
When the Boomer explodes, the arms disappear, possibly due to them being blown to bits. If the Boomers explosion is enough to destroy his arms as well as break glass and destroy wooden doors, it would more than likely do at least some damage to the Survivors. However, if one uses the command "z_Boomer_gibs 1", they can find bits of flesh, both arms, and the upper jaw of the Boomer among the bloody mess. The following commands "map MAPNAME" and "sv_cheats 1" need to be used beforehand because "z_boomer_gibs 1" has "game cheat" marked on it.
Judging by the weight and immensity of the Boomer, its body should have been able to restrict the Boomer from jumping higher than a foot or climb ladders, since the stress/tension would cause the Boomer's internals to strain and explode. However, for gameplay purposes, Boomers are given as much freedom as their Common Infected counterparts.
- Though judging by how the the Boomer explodes, it might be air or the bile instead of weight.
When examining the Boomer's navel, players can see the Boomer's intestines protruding from it.
A Boomer was apparently hit by a police car at the beginning of Death Toll, as a pair of Boomer legs are laying against the police car. This may be the reason for the large amount of dead bodies lying around the same area as if a Horde were summoned.

ZSGBoomer — Two *Boomers* surrounded by a crowd of Common Infected in the Zombie Survival Guide video.

Although large, pus-filled sacs are covering one of its eyes, it still has full vision, as seen in Versus mode, probably for game reasons.
The Boomer, along with the Tank, is the only Special Infected to have noticeable changes to physical appearance upon dying. For example, the Boomer's lower body only remains after exploding. In addition, the Tank's skin texture changes if it takes fire damage from Molotovs or Incendiary Ammo for example. However, none of the other Special Infected undergo any form of physical change upon death.
Along with the Witch, Jockey, Spitter, Hunter from Left 4 Dead 2, and the Tank found only in The Sacrifice, the Boomer is not wearing shoes. He is, however, wearing socks.
The female Boomer is referred to as "Boomette" in its model files. Currently, the Boomer is the only Special Infected to have both female and male models, and the first to have more than one model in general (The Witch being second and the Tank being third).
When playing as the female Boomer in Versus, the first-person view shows arms with boils, like the male Boomer has. As seen from third-person view, she does not have these boils, instead having blackened skin on her hands and slightly up her wrists that seems to have been caused by necrosis.
Normally, dead bodies tend to bloat, and when cut into, release gas. Though the Boomer is not a traditional "dead" zombie, this may be a reference to it.
In the Dead Center campaign, down the first set of stairs is a conference room: to the left is a poster board with pictures and graphs labeled "Boomer". The Boomer in the pictures are from Left 4 Dead and not the remodeled version. This suggests that CEDA named the Boomer. The Survivors from the first game may have picked up on this somehow, or it may be just coincidence that the two groups would choose to use the same name. This may be how the Survivors from Left 4 Dead 2 learned the Boomer's name, although it is still referred to as a "puker" in the first level.
The Left 4 Dead 2 Boomer seems to have a bite mark on the back of his head, suggesting that he has gotten the Infection from it.
In the Left 4 Dead 2 Strategy Guide, It shows the Boomer's Left 4 Dead design instead of his new one in his description.
When Boomer pukes on other Special Infected, nothing happens to it, but when Special Infected is hit with jar containing Boomer bile, it will have obscured vision (as seen in Versus) and horde will attack it.
An interesting note about Boomer bile in Left 4 Dead and Left 4 Dead 2 is that if puked on, one only needs to set their character to idle and quickly resume playing and their screen will no longer be covered in bile. However, you will still be covered in bile and therefore still attract a Horde. Note that this only works in Offline Co-op and Matchmaking.
Sometimes the game glitches causing a voice switch: A female Boomer may have a male Boomer voice or vice versa.
Biologically speaking, the liver creates bile. If that is the same "bile" that the Boomer releases, it raises the question if the Infection increases the size of his liver and/or its production of bile.
Boomers are the only Special Infected to not spawn during the Mutation "Last Man on Earth", since there are no Common Infected to be attracted to their bile, thus rendering them useless.
When an AI Boomer spawns on a greater height, it will strangely fall down, exploding like a Kamikaze, though if there were any Infected Ladders, it would ignore it.
The chances for a female boomer being spawned in the map can be altered by the player using these two console commands;
- z_allow_female_boomer - This value must be set to 1 (if 0, female boomers will never spawn, thus, ignoring the console command below.
- z_female_boomer_spawn_chance - (decimal number between 0 and 1) Set the percentage chance for a female boomer to appear.
In Left 4 Dead 2, female Boomers do not spawn on the maps from the original game, only on the new maps.
The Boomer is the only Special Infected that has captions given to it when it falls down from a distance. Other Special Infected do not receive this.
Boomers likely come from obese victims of the infection. Not only does the Boomer's bloated appearance support this, but also the fact that the liver produces bile for the body to absorb fat, as well as other nutrients. A high food intake may be a stimulus that caused Boomer's mass production of bile.

Gallery

See image archive for more images...

References

The Infected
Playable
Introduced in Left 4 Dead				Introduced in Left 4 Dead 2

The Boomer	The Hunter	The Smoker	The Tank	The Charger	The Jockey	The Spitter
Non-Playable
Introduced in Left 4 Dead				Introduced in Left 4 Dead 2		Cut Infected

The Witch		Common Infected		Uncommon Infected		The Screamer

The Boomer

Contents

Appearance

Extent of Mutations

Left 4 Dead 2

Female Boomer

Abilities

Attacks

Left 4 Dead

Left 4 Dead 2

Tactics

Survivors

Infected

Boomer Tips and Tricks Gameplay

Achievements

Survivors

Infected

Behind the Scenes

Notes

Gallery

See Also

References

Fan Feed