I understand that people don't like the low player numbers, so they jump through hoops and point to fringe edge cases that could potentially "hide" data. But the raw number is irrelevant without comparison to other games. What's actually interesting is the trend. All other games on SteamDB operate under the same conditions, so any imagined fringe exceptions would apply to them as well.
A more meaningful approach is to compare Civ7 to other games that had poor launches and faced consequences afterward. I couldn't find that many strategy games. Maybe you guys know of more that failed spectacularly.
Imperator: Rome
Release: 41,945
1 month: 2,623
2 months: 982
3 months: 833
Final DLC: Released a little under 2 years later / sporadic updates, but effectively abandoned
Player drop: 98% in 3 months
Humankind
Release: 55,284
1 month: 10,017
2 months: 3,022
3 months: 2,419
Developers eventually bought themselves out from SEGA and "went back to their roots" (paraphrasing) with Endless Legend 2
Player drop: 95% in 3 months
Age of Wonders: Planetfall
Release: 10,462
1 month: 1,768
2 months: 976
3 months: 499
Game was "stabilized" and development quickly shifted to AoW 4, which launched 3 years and 9 months later with 4x the player count
Player drop: 95% in 3 months
Compared to civ titles:
Civ7
Release: 42,553 (advance access was stupid)
1 month: 26,668
2 months: 11,776
3 months: 12,306
First weekend peak: 84,558
Player drop: 85% in 3 months
Civ6
Release (Friday): 142,779
1 month: 48,798
2 months: 29,292
3 months: 34,018
First weekend peak: 162,475 (never surpassed and not even close)
Player drop: 79% in 3 months
Civ5
Release (Tuesday): 39,886
1 month: 27,698
2 months: 27,031
3 months: 20,771
First weekend peak: 70,096 (record broken only after 2 years and 9 months with second expansion). All-time peak at 91,363.
Player drop: 70% in 3 months
Very strong player retention even if you look several months later.
In conclusion, civ7 likely sold an acceptable number of copies, but not enough compared to its predecessors. More importantly, it retains players worse than civ5 or civ6 - though not disastrously so. It doesn’t look like a product doomed to be abandoned, but the signs aren't encouraging either. I think retention rate would have to be much worse than it currently is.
Civ6 may have ridden the momentum of Civ5's success. Being part of a longstanding franchise brings heavy expectations, and I believe Civ8 will face serious challenges if it hopes to regain its predecessor's appeal. Something was was lost in civ6 and that continued in civ7. The "Ed Beach" era.
It's like macroeconomics - you won't see immediate results until many years later. Firaxis might think Civ6 was a major success, but I'd argue it was propped up by the goodwill of Civ5. Civ5 was just that succesful. They may have learned the wrong lessons. Civ6 was certainly better than civ7, but just the wrong direction for the franchise. The franchise isn't dead, but the trend is clearly downward.
It's a shame that there is no data for civ4.