Not quite true. Compared in the way you put it, COD has almost no advancements while AC improves their gameplay every game. They went from having to wait through cut scenes and hardly any free world roaming to much larger free world roaming, less loading scenes, and a more sophisticated engine over all. I can agree the AC2 series didnt have much of that but AC2, Brotherhood, Rev, can be said were the same game and story, literally.
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