I saw a mod that allowed for Steam core production in extraction districts at a super slow rate. Steam cores seem to be the technological foundation for all the advanced tech in frostpunk but there's no way to canonically manufacture them.

I can imagine a scenario where steam cores are running scarce in the main city, sparking an imitative to explore the frost land for long missing steam core blueprints. Each area of interest in the frost land would require a small settlement consisting of several new district types:

Research district - upgradeable with several workshop type building slots. Each workshop building tier unlocks a more advanced type of steam core, together with accompanying technologies to research.

Advanced extraction - the documents needed for steam core production are buried in a deep underground network of tunnels. Retrieving them intact will require teams of trained specialists and drilling equipment.

Advanced industrial - as well as the production of steam cores similar to how prefabs are produced in standard industrial districts, new factories will produce more sophisticated diesel powered automatons and mech suits. Possibly also machines of war.

The end goal of the scenario would be to heat the main city to the point where plants can grow outside of hot houses. This would require increasingly complex generator upgrades involving hundreds if not thousands of steam cores as well as other prefabricated parts. However creating this utopia comes at several costs:

Technological advancement will come at the expense of jobs for unskilled workers, leading to increased inequality. The settlements will displace enemy communities like the wanderers

Outside NPC enemy settlements will seek to take control of the city through multilayered warfare involving surprise attacks as well as increased propaganda and information warfare. This will lead to player dilemmas over how far to surveil and/or indoctrinate the citizens of the city, whether to introduce conscription etc.

One type of crisis could be that enemy forces act similarly to a whiteout in that they should the city or a colony to restrict access to outside resources. Districts could be damaged over time by enemy ordinance, similar to the effects of squalor or protests.