Don't Starve - Frostfire

[acing3]

I've been enjoying Hamlet immensely and it got me thinking. Almost every Don't Starve DLC has had an environment change, and that has added a fresh take on the original feel. This has gotten me thinking. What biomes have we not really seen from Klei? Frozen tundra and arctic biomes as well as the lava caves that we heard hints of way back a couple years ago. The contrast between an arctic overworld with lava caves would be an extremely interesting concept. Now obviously we have seen the cold element in ROG and OG DS, with winter making appearances, but what about an always winter landscape, with seasons like blizzards limiting LOS, hail that does damage over time without shelter, and stuff of that nature? But not only would seasons exist above ground, but the molten caves would have periodic heat waves and you would have to use hot springs above ground to keep warm? Just an interesting Idea I was thinking of as I was bug-testing Hamlet and I think it may have potential as a "Hardmode" of sorts.