BitMaster_1980: We are talking 4X and grand strategy after all. Compared to the likes of FIFA and shooters and whatever the cool kids are playing these days, they are extremely niche. According to a quick Google search, the entire Civilzation series with decades of name recognition sold less than 30 million copies. FIFA well above 300 million. Call of Duty above 500 million.
An immediate difference I see in what you're saying here is that every game in the Civilization series is quite different from every other. A screenshot from one is
instantly identifiable as to which entry in the series it came from. For the most part, you cannot say the same about the other series you mention. One reason is that those series are often built on the bones of their predecessors, to the extent that some reviews have even told players there's not enough new stuff in a new version to bother purchasing unless you're a die-hard fan of the series. I can't recall ever seeing a review of a Civ game that said something similar, because each one is a major re-imagining of what came before.
In other words, games like the Civilization series require a lot more originality of thought and ideas to create new versions when compared to series like FIFA and CoD, which pump out new, slightly-different versions year after year.
Also, I'm not sure where exactly your Google search led you, but it seems to have given you mixed results. My own search confirmed your numbers for FIFA and Call of Duty, but according to what I found your data for the Civilization series is less than half of the real number, which is between 70 and 75 million copies across the entire series. No, that still doesn't compare to CoD's totals, but it's not quite as niche as you're making it seem. Indeed, Civilization ranks
ABOVE such well-known franchises as The Elder Scrolls, Diablo, and Fallout, all of which I would have considered less niche than Civilization is.
Hell, the sources I looked at make series like
Zelda seem niche compared to CoD, at 170ish million sales. I would be willing to speculate that the Zelda series has had more of an impact on gaming than CoD ever will, even with 330 million fewer sales.
TLDR: I don't think I buy the idea that a game is "niche" just because it can't match the sales of the likes of CoD, FIFA, or some of the other big players in the industry that are known for mass-marketing very similar games. I don't think
any franchise that sells tens of millions of copies fits well into the definition of "niche" for that matter.