In this game mode all players begin on the same team, looking for places to hide and people to team up with during the first 20 seconds. Once the timer is up 1-2 soldiers are transformed (at random) into mutants whose soul objective is to turn all the humans into mutants like themselves. The humans have to either eliminate all mutants or, more realistically, survive until the time runs out. Soldiers get kills for dealing 1000 damage to a mutant and mutants get kills for mutating soldiers. Soldiers can hold back mutants by shooting them, which pushes them back depending on the weapon. As many of you have noticed, guns do not wear down through use during this mode. Consequently, your kills and deaths are not recorded into your stats.
These are the weapons used most in crossfire, regardless of the mode. This is a weapon primarily used for killing mutants. As the lower ammo capacity will leave you in a jam when trying to run the timer out without some help from friends
AK-47 (And variants) - The AK-47 is the rifle with the highest damage in the game and would lend itself to being a useful tool in this mode. As it performs in other modes, the ability to drain health from the mutants is unparalleled. When this rifle is being used from a camping position, i.e. The traffic light in Zone 13, it performs exceedingly well, provided that you use highly accurate single and burst firing. It's effectiveness is vastly reduced when used to spray at mutants or while running away. You will find that you will miss far more than you hit if you hold down the left mouse button, especially while moving. The push back on this gun is quite good, especially when pulling off head shots. A full clip will push a mutant far enough for you to reload without fear. The AK-47 variants (Camo, Silver) work just as well as the normal version, with the small benefit of a +5 extended magazine (+8 if Gold). Those extra bullets help as reloading during this mode is always risky. Head shots from this gun deal 200 damage and it takes roughly 3 chest shots to deal 100 damage. The general number of kills you will get per round with this gun ranges from 2 to 3. I would highly recommend this gun if you are the person that likes to take out mutants rather than outlast them.
M4A1 (And variants) - The M4A1 is a highly lauded rifle for its accuracy and low recoil, it also performs well in this mode. Even though this gun has lower power than the AK, the M4's higher accuracy makes it easier to pull off mutant head shots. Single and burst firing are necessary for this weapon as the higher rate of fire will have you burning through ammo quickly. This gun is slightly better when on the move than the AK as bullet spread is a little better. The push back on this gun is seemingly insane. A full clip will push a mutant far outside it's kill range, giving you time to reload and re-engage. The only variant I have used is the M4A1-Advanced, which performs better in the fact that it is harder for mutants to locate you by sound and has an extra +5 ammo capacity. Damage for this gun is 200 for head shots and 3-4 shots will give you 100 damage. Kills per round range from 1-3 on average. I recommend this gun if you prefer accuracy to power.
Scar Light - Called "The Noob Cannon" and "The Skill Light," this weapon performs fairly mediocrely in M.M. The gun's power is higher than the M4 but lower than the AK's, giving those who like it, a nice middle ground between accuracy and power. The recoil on the Scar-L is next to nothing for the first few shots and ramps up slowly their after, making it suitable for both single, burst, and spray firing. The high ROF will have you out of ammo quickly, so conserve as much as possible. It is suitable for moving from place to place while firing because the spread is quite tight. The push back is a little less than standard for an assault rifle, and you'll find it a bit lacking when compared to the M4 and the AK. The only truly outstanding thing about this rifle is the reload time. Reloading is what gets me killed most of the time, and this gun remedies that. Damage for this gun is interesting. Head shots are 200 damage as usual, but on the whole it takes 4-5 shots for 100 damage on the body. I suggest using this gun if it is your weapon of choice and you're comfortable with it. Don't buy it because you think it will beast in this mode.
Overview: The assault rifle is king in all other modes and they preform quite well in this one. The combination of power, R.O.F., and accuracy make it a great gun for killing mutants before they spread. Ammo capacity is what keeps this gun from being the be all and end all weapon of this mode.
Sub Machine Guns:
This is a weapon with a higher capacity of ammo, lower damage, lower accuracy, and lower weight than an assault rifle. This lends itself to a more mobile, "Run and hide" style of gameplay.
MP5 (And variants) - This is THE submachine gun, the one you will see most often in other modes and the one with the best reputation. It has one extra clip than most all the assault rifles and trust me, you will need it. The gun does a mediocre amount of damage to mutants and the push back on it reflects that. The fast reload counter acts this, as it takes 2 seconds or less to reload a full clip. The biggest advantage of this gun to assault rifles is the ability to run away quickly while still doing damage. This gives the soldier valuable time to rest and conserves ammo in the long run. Shoot in bursts or spray with this weapon, single shots are ineffective. The MP5-Adv is superior as it reduces noise, making it harder for mutants to find you and it extend magazines from 30 to 40 bullets. Damage is 100 for a headshot, which is rare and 5 - 6 shots for 100 damage to the body. Kills per round range from 1 - 2. This weapon will suit a player that likes to stay away from large groups, hiding and outlasting mutants rather than engaging them head on.
P90 - Always the second choice next to the MP5, it performs well if not better than it in this mode. Its ammo capacity is one of its greatest assets. 50 bullets per clip is nothing to laugh at in this mode, though it only has to mags in reserve. The recoil is higher than the MP5 so spraying is slightly less effective but the increased number of bullets means a higher push back per mag. It has an ability to take on multiple mutants at once, something the MP5 struggles with. This makes it easier for a guy with a P90 to survive during the late game when a veritable horde of mutants searches for you. Damage is 100 for a headshot and 5 - 6 shots for 100 damage to the body. Kills per round range from 1 - 2. Use this weapon if you like the security of having an enormous clip whilst still maintaining unparalleled mobility.
Overview: You have to be a smart, disciplined, and cunning player to use an SMG in this mode effectively. If you play to the gun's strength then you will find yourself looking at a "Soldiers Win" screen more often that not.
They boast the highest ammo capacity of any weapon in the game and have a high amount of damage. What they sacrifice is accuracy and mobility.
M60 - Some people might say that this gun was made for Mutation Mode. With its 100/100 ammo capacity running out of bullets will be one of your last concerns. As one would expect this gun performs beautifully, high damage and push back slightly less than that of an assault rifle. This is the gun to use when holding choke points. It has an amazing ability to hold off up to 4 mutants at a time, giving your team valuable seconds to reload or throw grenade. Reload is arguably slowest in the game, meaning you should have one or two of your buddies backing you up when you inevitably have to. Shoot in bursts or single shot it, spraying with this weapon will run down your high ammo count faster than you think, and with less effect. When trying to run or escape a mutant, spray and pray, the slow movement speed will mean you can't get out of sight. Damage for this gun is 200 for head shots and 2-4 bullets for 100 damage to the body. Kills per round can range from 1 - 4. This is a gun for those who like to help support their team in a big way.
RPK - A truly great addition to the game, this combines high ammo capacity, high damage, decent accuracy, and decent reloads to make an awesome gun. The gun has an 80/80 ammo count, less than the m60 but more than any SMGs and most assault rifles. This means that you have to conserve bullets more than those who chose the m60. What you get however, is increased accuracy and bullet spread. This gun is suitable for single shot, burst, and spraying. You will find that the recoil is incredibly controllable, and will get you a lot more kills and hits. Reload time is incredibly fast for a machine gun, though you still might need some teammates to bail you out when you do. The damage on this gun is higher than the m60 and will get you more kills in the long run. On the move, you really need to spray and pray, but keep your head. Use that big mag to your advantage. One other thing, it looks badass. Damage for this gun is 200 for a headshot and 2 - 4 for 100 damage to the body. Kills per round can range from 1 - 5. Thats a lot of kills. This is a gun for those who like a status symbol that functions as the backbone of a good mutant defense.
Overview: Their big, their bad, their quite useful. The biggest weakness with these guns will be the player behind it. It is quite possible to get complacent and sloppy when someone has that much ammo to play with. Discipline is required to make these good guns, great guns. If you play M.M. a lot, I suggest you pick one of these puppies up.
These are the campers dream, and the bane of those who can't aim. They perform adequately in support roles for M.M. One thing to note, push back is delayed on sniper shots. Meaning you will see the blood and a half second or later the mutant will be pushed back. This can mean the difference between life and death.
AWM - The obvious choice when looking at sniper rifles seems a little lacking in M.M. The biggest advantage of this rifle is the damage. One shot to the body will deal 100 damage and one shot to the head will deal a whopping 500! This is easy to pull off when holding A site in port or sitting on the circulation light in Zone 13. This gun is not one you can use sitting alone by yourself, you need people with automatics to support you. And if you have to run away, it's better to just throw it on the ground that try to fire while moving. Great if used correctly. Always have a back up, you will run out of ammo. Damage was listed above and kills per round can range from 3 - 6 depending on your aim. Use this weapon if you use it a lot in other modes, don't buy it specifically for this mode.
M700 - The little gun that could gets my vote for best sniper for M.M. The R.O.F. is much higher than that of the AWM and the real kick here is that it does the same amount of damage for a body shot, 100 per, though it only does 300 damage for a headshot. Accuracy is marginally higher, meaning you will get many more hits than misses if your aim is on. Reload is quick and manageable and it is far lighter than the AWM, meaning that vacating the premises will be slightly easier, though still inadvisable. Once again, don't try to lone wolf your way through a round with this gun, you will find yourself one of the first to go if you do. Damage is listed above, kills per round range from 3 - 5, though it could be higher depending on the aim.
Overview: Obviously not the first choice, these guns are used more for fun and dealing out massive damage to mutants over a short period of time. Get good with these puppies and mutants will drop like flies. If you can't aim, you'll be smashing your computer faster than you can say "Mutants Win."
Last resorts on the battlefield, these weapons are surprisingly formidable in this mode. Providing speed and power to get you through those final seconds of any round.
Desert Eagle - The first choice in terms of personal defense, this pistol performs well in this mode. It has a low ammo capacity, as do most pistols, but high damage which makes it a good back up. The mobility this gun will offer is surpassed only by running with a knife, meaning you can dish out a lot of damage while still running away. It has massive push back for a gun its size, giving you precious time to reload. Damage is 200 for a headshot and 2 - 3 shots for 100 damage to the body. Kills per round range from 1 - 2. I suggests this gun for your back up in this mode due to its low rank requirement and high damage output.
Anaconda - A formidable opponent to the Deagle if put in the right hands. It has higher accuracy than the deagle at the sacrifice of some power and R.O.F. It also has a much faster reload and draw speed. Meaning if a mutant is about to get you, it is advisable to draw this gun rather than reloading. Its mobility is high, making it easy to run and deal damage while trying to run the timer out. It's easier to pull off head shots with this gun, making its maximum capacity for damage is generally higher than the deagle. The push back on this gun is slightly less than that of the deagle, but is made up for by the faster reload speed. Damage is 200 for a head shot and 2 - 3 shots for 100 damage to the body. Kills per round range from 1 - 2. I suggest this weapon if you can aim for the head well while moving, and if you like looking like a badass.
Overview: The pistol in this mode is an essential accessory to any backpack for this mode. If you don't have time to reload, being able to pull another weapon and keep firing can save you more often than you think. A must have for everyone playing this mode.
Otherwise known as "Oh SHIIIIIIIIIIIII-"
Regular Knife - If you have to use this weapon, consider running rather than fighting. There is something however to be said for those who can "Dance with Mutants." This means jumping into mutants at strange and random angles rather than running away or jumping backwards. A good mutant dancer can survive up to 20 seconds amongst a horde of mutants wielding only a knife. Stabs do 100 damage per body shot and 200 for head shots. If you are fantastic at this, you can get a kill every round with it.
Overview: The round is almost done, 10 seconds left, you're the last soldier alive. The horde runs at you, slavering for blood and that one kill bonus. But whats this? You jump like a mad man into the horde, they swing at you but not one connects, the players are confused and boggled. Before they can get their bearings the words flash by. "Soldiers Win." Score one for humanity.