It can be argued that the experience of a first person shooter is actually the act of being a sentient roaming gun. Though some 2nd Amendment debates would hold this is the case in reality, it could be more reasonably articulated that it is in many ways the case in games. On a technical level, often the player is just a bounding box with a weapon visible, perhaps some hands, and in multiplayer they are displayed as a character to other bounding boxes with a weapon visible. Metaphysically speaking, now that sounds fancy, the primary input with the game world in an FPS is simply shooting (particularly in the Quake franchise which centers its logic systems around damage or proximity) so obviously the gun at hand is a primary source of expression.
This however is greatly impacted by the inventory and spawning system of the game. In the Quake and Unreal franchises you spawn with a certain supply of weapons, and you find others in the environment. The weapons are expressions of discovery, what you have found, they represent exploration and knowledge. These weapons are also usually fairly distinct, sure they can be broken down by simply hitscan or projectiles, but no one is going to argue that Quake Live’s (and thus Quake 3’s) Plasma Gun and Rocket Launcher are particularly similar weapons. The weapons are intentionally as distinct as their location in a level and are designed to occupy a large range of design space within the scope of the mechanics.
Counter-Strike ties weapon accessibility to player progress and earnings, with an emphasis on distinctly increasing power. The gun represents how far you have come in earlier trials and is meant to give an advantage rather than provide a particular role. It has a degree of prestige to it, as well as general position, that weapons in other games would not.
Now we come to the pink camo elephant in the room, Call of Duty. As you pick what weapons you spawn with, they cannot represent discovery. If they are substantially different in power then everyone will just pick that particular weapon, so it is considered a design flaw in the game, thus they cannot be a display of prestige or power. The weapons in Call of Duty are the expression of the player themselves. They are their tastes, preferences, what they want to be, how they want to be seen. In this they rely on minor differences that compound in edge case scenarios. With player level progress, more guns are unlocked but in the framework of variety rather than power. An M27 is at a glance just another MTAR, until you play with it. It will fit better, or worse, with your sense of who you are in the game. (For a reference point, the MTAR is a 3-5 shot kill decent in all jobs assault rifle. The M27 is a 4-5 shot kill assault rifle with bad hip fire but minimal recoil and is relatively unaffected by the use of a suppressor.)
That sense of expression is expanded on with unlockable camos, reticles, attachments, and the ability to reset progress on it for the purpose of adding clan tags and personalized emblems on it. That gun visually represents you, and expresses what sort of player you want to be. You come into every life with it, and it is you.
Mechanically, it is worth noting a major divide in first person shooter mechanics: major differences, and minor differences. Quake, Unreal, et al engage in larger differences, where weapons are orders of magnitude more powerful than one another in their given situation, where powerups multiply your own damage or survivability. Call of Duty engages in minor differences, where every exchange is theoretically a close one. You win by a hair more often in its fights, a reason for the perceptions of intensity behind the franchise, and thus the particulars of a given gun matter more, as they must fit into matching that mold of your own skill set, so that you come out on top, ever so thinly. I have compiled a list of variables I am aware of which are unique to each gun’s class, and most of which are unique to each gun. They are also all modifiable by the various attachments.
- Max Damage
- Min Damage
- Damage falloff profile (multiple values)
- Hip sway
- Hip reticle spread
- Hip reticle walk spread
- Hip reticle crouch spread
- Hip reticle prone spread
- Sprint recovery
- ADS sway
- ADS visual recoil
- Recoil kick
- Recoil angle
- Recoil accumulation
- Recoil decay
- Draw speed
- Equip speed
- Dequip speed
- Empty reload speed
- Tactical reload speed
- Reload type (magazine, clip, belt, individual)
- Loaded amount count
- Additional ammo count
- Firing style (single, semi, burst, full)
- Firing interrupt
- Fire rate
- Firing profile (accelerating, decelerating)
- Movement speed
Now multiply that by attachment count, and possible combinations (in many Call of Duty games you can have two, in Black Ops 2 you can have three), and you will find a great range of expression as a player. Yes, at a glance they are just bullet sprayers, but at a glance the Quake or Unreal arsenals are just projectile launchers. Quake and Unreal use overt mechanics and styles to convey, Call of Duty uses minor changes, and the factors above are what get tweaked in balance patches, to much drama. The minor differences makes for a scenario of finding the weapon that fits you like a glove, rather than finding a weapon that is well enough. It is simply a different end goal for the game in its armament system. We can set aside for now the existence of the crossbow, ballistic knives, tomahawks, launchers, claymores, bouncing betties, tactical grenades, sensor grenades, and more, but keeping them in mind, the game does offer more than minute differences between bullet launchers.
That is the crux of it though, the obliqueness of grouping titles within a major genre without acknowledging in full the differences in sub-genre. Call of Duty isn’t different from Quake because it is a modern military game or a linear single player story. It is most different because the player expression and reward models are different. At the end of the day I strongly prefer Quake over any Call of Duty or Battlefield game, but I can see what they are trying to do. Whether or not they succeed comes down to the play experience with each release.