I asked devs about a cave map and I got this reply:
We've talked about cave maps, they're just harder to make since those assets need to be modeled and tested. Unfortunately, the modeling and the testing aren't done by the same person/people so there would be a bunch of lag time developing a map like this. If we ever do manage to get to a cave map, it will be for co-op.
For anyone interested.
Also I assume mines or just pure cave or a mix would work fine..
