Another weird thing is how few games rip it off 1:1. There was Battlefield, and Titanfall 2 (which is amazing) and that's about it unless you get into obscure games.
I can think of like three games for this type of thing, Warface, Ironsight, and XDefiant.
Warface released sometime in 2013, and is somehow still alive, but it's barely kicking. I don't think this game was made to be a true Call of Duty competitor, but the game played almost exactly like it with a few quirks like a Battlefield style class system of Medics, Heavies, and Engineers, which restricted weapon choices based on what you chose if memory serves me right. The game also featured hot swappable attachments where you can swap out scopes, suppressors, and grips on the fly. It was a decent game and I enjoyed playing it when it was on Xbox 360 and even a bit on PC, I wouldn't touch it now though.
Ironsight was released in 2018 and was a true "CoD Clone." When it came out people often compared it to Black Ops 2 in style and gameplay, as the game had a near future aesthetic with the game taking place in a way cooler 2020's than what we got now. The game had it all, just watching gameplay of it you can just straight up see that it was trying to be F2P Diet Coke CoD, similar animations, hitmarkers, sound design, UI, it even has the Treyarch style scorestreak system. The game is still up to this day, surprisingly, but after the hype died off, people didn't bother to stick around since there was no proper grind in the game that is commonly associated with CoD. No camos, attachments you bought with earnable currency, character items and skins were pretty much all only purchasable with earnable/buyable currency. That and the game just being CoD, most people would rather stick to what they're used to and play CoD.
XDefiant, developed by Ubisoft and after multiple beta sessions the game was released May 21, 2024, and will die on June 3, 2025. Ubisoft was trying to go for the throat of Activision with this game, it was a straight up CoD ripoff. The development and hype cycle of the game was interesting, since the game was being tested and teased around the mid point of the lifecycle of Modern Warfare II, which was a very contentious game in the CoD community. People were not happy, so a lot of people were kind of looking for an alternative, so XDefiant looked to be the next best thing. However, the game's actual full release was right in the middle of the life of the "newer" Modern Warfare III. This was bad, very bad for Ubisoft. Despite MWIII being a rushed, recycled piece of shit, it was one of the more enjoyable years for Call of Duty because of the constant support, post launch events and content, along with the developers being a lot more communicative than Infinity Ward which helped a lot with repairing community relations from the semi-disaster of MWII. All of this hype from CoD ship-jumpers was essentially gone, despite that the game still got around one million unique players on launch day, however it would be proven with time that Ubisoft would struggle keeping a fraction of these players. There's a whole list of issues that XDefiant had that I won't go too in depth about (believe me, I would fucking love to since I absolutely hate this game with a burning passion). But like I said at the beginning of this autistic paragraph of useless drivel, XDefiant is only going to last only a little over a year. On December 3, 2024, only around seven months after the full launch, the game's producer announced that the game would be eventually shutting down. Rest in piss, this is what happens when you make a shitty knock off of a game with a horrible visual style and aesthetic along with having absolutely zero skill based match making.
Along with that, I'd argue that Titanfall is not a CoD ripoff or clone. Yeah it's a "CoD-like" but it has enough quirks, ideas, and gameplay features to truly stand apart from it being just another cash grab trying to steal the CoD playerbase. It's also the type of game that they're probably most familiar with, since Respawn was founded almost entirely by Infinity Ward old blood, who funnily enough would go back to IW to work on Call of Duty again to make the 2019 Modern Warfare reboot.
And I guess for thread tax, Call of Duty is a quality product. Despite the issues with bugs, AI content, or not being "original" anymore. You know what you're getting, no other studio has truly been able to replicate the smooth gameplay style of Call of Duty, and as previously discussed in the post, most who tried have failed miserably. There really is no other FPS game of its caliber out there, and probably won't be for a long, long time.