nimble grove
-Endless mode that starts during the Last Autumn, so that you have to build the Generator before the winter sets, otherwise it will be cold and effectively you'll be partway into the current builder start.
-Land expansion. Depending on the map expansion via icebreaking would be different, and of course it would take time similar to building a generator, with newer tech allowing faster and further expansion, to a limit.
Such as on the Winterhome map where there is a large snow wall that could be breakable.
You could also implement so that you can build an elevator similar to a sloped elevator, allowing for expansion on the ice shelf, with wind barriers as a constructible to "increase" the heat by reducing wind impact on chilling.
-Multiple Generators, either adding locations for smaller ones to the expansion areas, or possibly full generators to new locations, where you have to sacrifice time in one city to build and manage another, so ideally you would wait for four first to be self sufficient in resource management, but you don't necessarily have to if you want a challenge.
-(Just a personal preference her) Full scale live map, so expeditions, cities, and locations are on a full live map instead, and time continues when you zoom out in a continuous map.
This could also make the game prime for a FP1 experience with tech and time up to what FP2 finishes with.
old chasm
toxic dagger
deep jackal