It’s also possible I’m wrong, I never played the games before CIV6 (or not enough to learn them), but on Fdroid it’s described as an “Open source 4X civilization-building game” which I assumed means it’s a CIV4 clone.
Either way, it’s a good game - one of the best open source mobile games for sure.
I had no idea, thanks!
For other unenlightened lemmings:
4X is apparently an abbreviation of “Explore, Expand, Exploit, Exterminate”
https://en.m.wikipedia.org/wiki/4X