Posted this in the discord so I'm just gonna copy and paste it:
I think that a really cool addition to the game (although likely very complex) would be geothermal farming near hot springs. I know that the ground near hot springs are very toxic to plants so maybe the plants would have to be raised above the ground and yielding half or less produce just to balance the winter aspect of the game. Or maybe chutes could have another purpose like transporting steam to somehow heat up a greenhouse without the steam poisoning the plants with heavy metals or sulfur. I think it could also be cool if there was an industrial aspect of hot springs where it is possible to harvest passive sulfur or other heavy metals. Last of all another possible use for hot springs that i think could also be pretty nice could be heated bricks for easier warmth in winter. I think that this could add quite a lot of use for late game copper although pretty advanced for the time period I would think the game takes place in.