Frostpunk 2 brings in a map literally called The Pit, a revamped heating system, and a lot more in its first big update
Cool!

What do people that play Frostpunk call themselves, frostpunks? Feels too obvious, but I'm going to do it anyway. Breaking news frostpunks! There's a new big Frostpunk 2 update that's just arrived in the game, adding some pretty big additions and changes,so let's jump into them. First up, The Pit! No, it's not just some hole to chuck things in, it's a large new map with a "distinctive 'proto-crater' pit counted as mountain terrain," to be found within.
The heating system has seen a big overhaul too. Described as the "biggest systemic change since launch", this one localises heat management to individual districts. Each district can apparently have "unique" effects, as well as consequences if you're failing to keep places warm. There's a new heatmap view too so you can see how each district is doing temperature.
Serenity mode from the first game is back with this update, a good one for frostpunks that don't like stress. There's gentler weather, way more resources, shorter whiteouts, and the fervour system is completely gone, meaning no conflict between factions and very few protests.
You'll find new challenges in-game too, all of which apparently introduce a "unique quest and storyline. Multiple Tales can be combined in a single playthrough. Complete a Tale to unlock a unique Monument Hub to “decorate” your city, but be careful: failure results in game over!"
The strategy game has received a few other tweaks to smooth things over as well, like a rebalanced prologue, improved tutorials, city visuals showing a denser population, alongside other changes. Modding tools are out of beta now, adding in features like a search bar, improved loading times, and tutorials.
11 bit studios go into a lot more detail about the minutiae changes in a Steam post, if you're looking for all the nitty gritty bits. There they also promised that alongside future DLC, they are "committed" to releasing more free big updates for Frostpunk 2, all while they work on the recently announced Frostpunk 1886.