In order to be more realistic & encourage cave use, any tile with an overhead mountain should have a strong preference (heating or cooling) to 10'C.
This would give tribal players on ice sheets a fighting chance. And give players who want a greater challenge a reason to play on Small Hills or Flat.
And encourage more dwarvery. Diggy diggy hole!
Fully agree. Areas deep in the ground (if they are ever added) or deep in a mountain should cause the temp in those areas to be relatively stable. Realistically those places keep a constant temp of around 14C (57F) on Earth no matter if the outside climate is scorching desert or frozen tundra. Currently there is little to no reason to use a cave for shelter in the game aside from mortar protection, and that is a late game problem.
It would make tribe starts feasible by providing an easier method of protection from the elements and early refrigeration. I hate that my tribe is building steel buildings instead of living in a cave for the start of the game.
I also totally agree with this. I've been avoiding mountainous/hilly starts thinking this was already in the game and thus would be too easy. But it certainly should be there!
Tynan added the infestation event to specifically avoid/impede "dwarfism", actually.
But, otherwise, I agree. I prefer to not use power, and digging some root cellars (https://en.wikipedia.org/wiki/Root_cellar) is how I usually go about it.