If you've played Call of Duty your entire life (or, at least, these pasts few years), you'll know that every single game follows a similar structure or formula. It doesn't matter if it's the single-player campaign or the uber-popular multiplayer component - every new Call of Duty game is more or less a prettier version of its predecessor, for better or for worse. However, veterans also know that each Call of Duty game feels very different.
At its core, every Call of Duty game has different guns, movements, and even visual styles, even if they're only released a year apart.
People used to defend the game by saying that it's up to the developers, as Treyarch, Sledgehammers, and Infinity Ward previously (and still do) take turns leading the development of each new Call of Duty game. But, the truth is, the jarring changes all boil down to the lack of engine continuity. 2019's Modern Warfare and 2021's Vanguard used the same engine, but 2020's Black Ops - Cold War didn't.
Even though Infinity Ward will likely offer some familiarity with this year's Modern Warfare 2, Activision Blizzard confirmed that all games going forward will feel and play the same.
Activision's communications director, Stephanie Snowden, explained to GamesRadar that the new Call of Duty engine will use parts of the popular IW engine but will also integrate portions of the engines used by the other studios.