I doubt Canadian First Nations are a major gaming demographic. For a civ to have marketing appeal it needs to be of interest to the global Civ audience - targeting even a large single-nation market with a civ that has limited appeal anywhere else is not sound marketing. For large groups like this, it seems more likely that their size makes them more recognisable in pop culture than other societies from that region or represents genuine regional importance, as well as more accessible linguistically and in terms of their history. I doubt the fact that Quechua is the largest indigenous language group in the Andes was a factor in including the Inca - rather, they were chosen because they were recognisable and regionally significant, and the fact that members of their language group are widespread today is partly a consequence of that, not the reason for their inclusion.
I believe it was probably a combination of several things:
1. Testing the waters for a Canada civ and trusting that any Canadian representation would like sell copies in that region.
2. Hoping that there might be players of Cree descent who identify with the civ enough to buy the game.
3. Hoping that there would be a greater chance of players being personally familiar with the Cree enough to be an "ally," even if they are not Cree themselves.
And I think this mentality could explain a lot of why they have chosen rather populous tribes.
Nope, also in Argentina.
Firaxis had a stated goal in Civ VI of filling out areas that had no TSL representation in past games. I don't see anything more to adding the Cree and the Mapuche than that they were in civ-poor areas on the TSL map and had at least some name recognition compared with alternative groups from those areas.
I think it's multifaceted. Obviously the devs have been focusing on filling out the map. But then they could have also just used Canada or Argentina. So I think there are other factors at play, including in the Mapuche's case how to best represent both Chile and Argentina with one civ.
Scotland probably was chosen for popularity, but not because of the size of Scotland. There's a reasonably sized American demographic that claims links to Scotland - moreso than Ireland.
Okay I will grant you this, but it still kind of supports my point. The fact that Scotland had a mini overseas empire for a short time ultimately paid off more for it than Ireland because there are people in Nova Scotia and American who self identify.
But I will say that everyone in American is Irish on St. Patrick's day, so the race between the two was always very close.
Denmark didn't compete with Sweden, it competed with Norway, which has a somewhat smaller population. Sweden isn't a Viking civ. Either way appealing to the gamers within a country of fewer than 6 million is not a good sales pitch.
Mmmmm kind of. Denmark has the luxury of having been not only a Viking power but also a Scandinavian power. In that respect it has two different periods with different identities. It could either be competing with Norway ala Cnut. Or it could be competing with Sweden ala Margaret. The fact that Norway was already in the game all but removed Denmark from the first race, so it only had a horse running against Sweden.
I haven't seen anything that suggests Civ VI is selling at anything close to the level Civ V did. It outsold Civ V in 2018, which is not altogether surprising - but Civ V itself still sold well enough so long after release to be in Steam's 'bronze' category. Even now its player numbers on Steam are only 3,000 higher than Civ V's and it wasn't until after the last major patch that it overtook Civ V's playerbase at all, so unless a lot of people bought in and aren't playing it's performing well below Civ V when that game was current. Civ V spent years within the Steam top 10 - Civ VI is currently putting up what might be its best performance, at no. 10 exactly.
That's just it though. People haven't been buying into VI. They've either been veterans who are sticking with V until VI gets good. Or they've been noobs who didn't even know they wanted civ until it released on iPad and Switch. On top of that, VI is killing it with respect to diversity representation, and I absolutely bet that more female gamers are hopping on board, as well as more casuals who wouldn't have bought the game but for gimmicky identitarian civs like Canada and Scotland. For some people, just being able to build a hockey rink was the tipping point, and I would bet that demographic is not insubstantial.
It will remain to be seen, but everything about VI indicates that they are attempting to maximize appeal. Modern relatable civs alongside ancient pedantic civs. Greater cultural authenticity and diversity. Greater gender, age, and body type diversity. Piggybacking on the Disney aesthetic. Everything indicates this should sell better because it is not only more fun and simulating by design than V, but more inclusive. It is poised to be the tentpole V could have been, and will continue snowballing for as long as Firaxis wants to support it.
So, of course V is the standard to be beaten. But to my mind VI is doing everything right to so even better.