Underground Provinces.

[Skirmisher]

Originally Posted by Edi

First off, this is a question of mapmaking. Not modding. The two things are similar, but they work with some very significant differences.

OK I understand. Right now I just use a random large map against 4 random AI opponents. I haven't seen any evidence of caves in those maps.

[Herode]

Originally Posted by Skirmisher

OK I understand. Right now I just use a random large map against 4 random AI opponents. I haven't seen any evidence of caves in those maps.

I never saw any underground province in a random map. I guess the random generator ignores them.

You can also add "Caves & Corners" to your map list : 4 players and a full level of subterranean provinces.