Comment by BlueTemplar

I suspect that Minecraft might have the open source possibilities (or at least programming interfaces ?) that the other games you listed lack ?

For Civilizations, the more recent they are, the more closed off they tend to be : Civ 1 and/or 2 have basically been remade from scratch as open source, Civ 4 has most of the game open sourced in the two tiers of C++ and Python... but AFAIK Civ 5 (and also 6 ?) were large regressions in modding capabilities compared to 4 ?