Call of Duty game engine mechanics

As with every video game, there is extensive math behind Call of Duty, which decides the outcome of gameplay. This article focuses on the game's mechanics.

Movement
Sprinting increases the player's movement speed by half of its base value, and all weapons have the same sprint duration except the M21 and the P90 in Call of Duty 4.

Contrary to popular belief, switching weapons has no effect on mobility, with the exception of Call of Duty: World at War and Call of Duty: Black Ops.

Call of Duty 4: Modern Warfare
Movement speed is determined from the player's primary weapon upon spawning.
 * All shotguns and SMGs have base movement speed values of 1, with the exception of the AK-74u.


 * All sniper rifles, assault rifles, and the AK-74u have base movement speed values of 0.95.


 * All LMGs have base movement speed values of 0.875.


 * Overkill can be used to achieve a higher mobility rating. For example, a player with a shotgun as their primary weapon and an LMG as their secondary weapon will always have full mobility.


 * Extreme Conditioning doubles the player's sprint duration.


 * In the PC and Wii versions of the game, the P90 and M21 both have sprint duration values that are 1.75x that of all other weapons. This was patched on both the Xbox 360 and PlayStation 3 versions of the game.

Call of Duty: World at War
Movement speed is determined from the player's weapon that is currently equipped.
 * All shotguns, SMGs, sidearms, the FG42, and the M1919 have base movement speed values of 1.


 * All bolt-action rifles, rifles, and the BAR have base movement speed values of 0.95.


 * The Type 99, DP28, and MG42 have base movement speed values of 0.875.


 * Overkill and Extreme Conditioning remain completely unchanged from Call of Duty 4.


 * Switching to the Bazooka drops the player's movement speed value from whatever it was to 0.75.

Call of Duty: Modern Warfare 2
Movement speed is determined from the player's primary weapon upon spawning, as in Call of Duty 4.
 * All SMGs and sniper rifles have base movement speed values of 1.


 * All assault rifles have base movement speed values of 0.95.


 * All LMGs have base movement speed values of 0.875.


 * The Riot Shield has a base movement speed value of 0.8.


 * Lightweight gives the player a constant mobility multiplier of 1.07x.


 * Marathon gives the player an unlimited sprint duration.


 * When using One Man Army, the player's mobility will change with their primary weapon.
 * While using the P90 with the Extended Magazines attachment, a player's sprint time will increase to 7 seconds (75% bonus).

Call of Duty: Black Ops
Movement speed is determined from the player's weapon that is currently equipped, as in World at War.
 * All shotguns, SMGs, sidearms, special weapons and equipment have base movement speed value of 1.


 * All assault rifles and sniper rifles have base movement speed value of 0.95.


 * All LMGs have base movement speed value of 0.875.


 * All launchers have base movement speed value of 0.8.


 * Lightweight gives the player a constant mobility multiplier of 1.07x.


 * Marathon doubles the player's sprint duration, and its Pro version gives the player unlimited sprint duration.


 * Movement speed can be modified in Custom Games, to make the player move faster or slower. The player can multiply the movement speed by up to 200%.


 * Also because of the perk modifiers, a player can modify Lightweight for incredible speeds.


 * While sprinting, it is possible to Dive to Prone.

Call of Duty: Modern Warfare 3
Movement speed is determined from the player's weapon with the lowest mobility. For example, a player using an SMG replacing his secondary with an LMG (either through Overkill or by picking it up from the ground) will move at 80% speed.

The Speed proficiency increases movement speed by 10%, but only when using that weapon, so a player with an LMG with Speed and a pistol will move at 88% when using the LMG and at 80% when using the pistol.


 * All shotguns and SMGs have base movement speed values of 1.
 * All assault rifles have base movement speed values of 0.9.
 * All LMGs have base movement speed values of 0.8.
 * The bolt-action sniper rifles and the Dragunov have a base movement speed value of 0.9, while the rest of the sniper rifles have a base movement speed of 0.8.
 * The Riot Shield has a base movement speed value of 0.8.
 * All secondary weapons (including launchers) have a base movement speed value of 1.
 * Becoming a Juggernaut reduces the base movement speed to 0.52
 * Becoming a Juggernaut Recon reduces the base movement speed to 0.6
 * Extreme Conditioning doubles the player's sprint duration.
 * Also, using the USAS 12, MP9 or Skorpion multiplies the duration the player can sprint by 1.75. Combining one of those weapons and Extreme Conditioning extends the time you can sprint to 3.5x higher than normal, 14 seconds.

Stances
Stances are a position that the player's character assumes that has the capacity to affect their movement speed, accuracy, and fire exposure. The three stances have been common to the series since the first game.


 * Standing: The player is fully standing and capable of moving at 100% of their mobility (defined as the base speed multiplied by the movement speed multiplier of the weapon). This stance is also the only stance in which the player can sprint. As a result, this stance is best when on the move or when it is necessary to move from cover to cover. However, while standing bullet spread is increased, and the player is a larger target to the enemy. In addition, standing players make noise when they run, which allows them to be heard by enemies.


 * Crouching: The player is crouched to about half their height, and moves at 60% mobility. While the player moves slower, they are capable of taking advantage of cover that is about waist-height, and their accuracy is increased. Crouching players do not make noise as they walk around (except in Modern Warfare 3), making it the best stance for sneaking up behind an enemy unheard.


 * Prone: The player is prone on the ground, and moves at 15% mobility. The player moves extremely slow, but they present a very small target to the enemy at longer ranges. Accuracy is also best when prone. Prone is best utilized to take full advantage of cover, when taking shots at targets farther away, or to minimize damage taken in close quarters combat.


 * Lifting: In certain situations, such as in "One Shot, One Kill" (a singleplayer mission in Call of Duty 4: Modern Warfare), the player must carry another character. While the player moves at 100% speed, the player is unable to fire a weapon, preform a melee attack, sprint, or vault over obstacles until the character has been put down.

Health
A player's health is determined by the game mode being played.


 * Normal (or Core in World at War and Black Ops) mode health: 100


 * Hardcore mode health (or Miniscule in Private Matches): 30


 * Double health (or Old School in Call of Duty 4): 200


 * Health regenerates after being hit and not killed, except in Hardcore and Old School, which do not feature health regeneration.


 * Five seconds after surviving the most recent damage, ALL health is restored when normal health regeneration is on.

Weapon and Explosive damage
Every weapon in the game deals a set amount of damage. As the range between the player and the target increases, damage is reduced until it reaches a set minimum amount. These charts show each weapons' damages, ranges and reload times, among other things.

Call of Duty: World At War






Modern Warfare 2
Interactive Modern Warfare 2 Flash Chart

Weapon Behavior
There are many more in depth statistics which determine weapon behavior. One of the most important things to take note of is that guns in Call of Duty do not shoot bullets. Instead, they shoot Hitscans, which are perfectly straight, infinitely thin lines that travel at an infinite velocity. All hitscans travel forever except for those fired from shotguns, which disappear at a set distance. This means that all weapons in Call of Duty, excluding things that obviously do not use hitscans, such as the RPG-7, are perfectly accurate at an infinite range while aiming down the sights. Misses are caused by idle sway, recoil, and lag. Idle sway is the movement of the weapons sights without any input from the player. (In Call of Duty Modern Warfare 3, all weapons now feature idle sway, where as previously only certain weapons had idle sway.) Recoil is the movement of the sights while firing. Idle sway is simply determined by two numbers; idle amount and idle speed. Recoil is slightly more complex. It is determined by five numbers; maximum horizontal, minimum horizontal, maximum vertical, minimum vertical, and center speed. Each gun has its own set of numbers. Every time a shot is fired, the game randomly chooses two numbers, one for vertical recoil and one for horizontal recoil. These numbers will be in between the weapon's maximum and minimum values for each shot. If a number is positive, it is right or up, and if it is negative, it is left or down. Thus, if a weapon has a positive minimum value or a negative maximum value, it will always kick in that direction. Center speed is how fast the sights reset after firing. It takes effect immediately upon firing, but during fully automatic fire there is usually too much recoil for the sights to completely re-center after each shot. Low recoil is a result of a high center speed, minimum and maximum numbers having low absolute values and balanced values on all sides, and the weapon's rate of fire. Recoil values do not stack, meaning that the next shot fired will kick however much it will kick regardless of whether or not the previous shot has finished kicking. However, because it kicks from wherever the sights were, rate of fire plays an important role. Some weapons, such as the P90, fire fast enough that the high rate of fire actually reduces recoil because multiple shots come out before the gun starts to kick noticeably, while others, such as the MP5, fire slow enough that the next shot will end up coming out at the peak of its recoil, which greatly increases recoil. This was done on purpose to balance weapons so that some could have low recoil and a high rate of fire while others could have high recoil and a low rate of fire. However, this only applies to a weapon's base rate of fire, as that is how the game was balanced. Because of this, using Double Tap or Rapid Fire will almost always lead to a considerable increase in recoil.

Time to Kill
Time to Kill, usually abbreviated as TTK, is how long a gun takes to kill an enemy from the time the trigger is pulled until the target is dead. In many role-playing games, players use damage per second, or DPS, to determine a weapon's effectiveness. However, in a shooter such as Call of Duty, where everyone has equal health and firefights are very fast, it is far more beneficial to determine TTK than DPS. To calculate a weapon's TTK, all that is needed are damage values and the delay between shots. For example, a gun that fires at 750 RPM has a delay between shots of .08 seconds. If that gun does 30 damage, it takes four shots to kill. The first shot comes out the instant the trigger is pulled, so the formula for determining a weapon's TTK is d(s-1), where d is the delay between shots and s is the number of shots needed to kill. This means that any weapon that kills in one shot will technically kill in zero seconds flat. Because most weapons lose damage over range, it can be necessary to perform multiple TTK calculations for a single gun. Beware that even a few missed shots will greatly increase a weapon's TTK, so it can be beneficial to plug in different amounts of misses using the formula d(s-1+m), where m is the number of misses. Weapons with low recoil are the most likely to actually reflect TTK with no misses.