Call of Duty game engine mechanics

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

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


 * Normal (or Core in WaW) mode health: 100
 * Hardcore mode health: 30
 * Double health (or Oldschool in CoD4): 200
 * Health regenerates after being hit and not killed, except in Hardcore and Old School, which do not feature health regeneration. The exception to this is in Call of Duty: Modern Warfare 2, which includes health regeneration in Hardcore modes.
 * Five seconds after surviving the most recent damage, ALL health is restored when normal health regeneration is on.

Weapon and Explosive damage
Call of Duty 4 Weapon Stats

Call of Duty: World At War


Credits for these weapon charts goes to Den Kirson.

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 shotguns and 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. 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 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. TTK may also be affected by other factors, such as lag, however, the game mechanics do not account for lag, as that is a network issue.