Higher climbs get colder, so upgrade warmth
The official description says the higher you climb, the colder it gets, and it names warmth as an upgrade next to the pickaxe and backpack.
The sentence that decides the upgrade
Fetched wording: "Don't freeze, the higher you climb, the COLDER it gets!" The same description later says "Upgrade your warmth, pickaxe & backpack!"
- Cold is tied to climbing higher, not to a named biome list.
- Warmth is the upgrade whose name matches that cold. The description does not say a stronger pickaxe raises temperature.
- The backpack is a third named upgrade. Nothing in the text says it stores heat.
Numbers this page will not invent
No warmth capacity, drain rate, freeze penalty, or upgrade cost was in the 23 September 2026 description, the empty group shout, or the game-pass request that returned 404. If the in-game shop shows a price, that price is newer than this page.