The sun has been completely blocked out by a megastucture built at the lagrange point of the planet by a powerful outside faction. The planet is doomed to slowly freeze to death. You were traveling when the construct was completed and have a decent stockpile of supplies and some pack muffalo.
The world will gradually get colder until the outdoor temperature reaches about -200 C
Recommended mods:
Tier 2 Temperature, for the powerful heaters so you don't need to have rooms full of them
https://steamcommunity.com/sharedfiles/filedetails/?id=1798787901&searchtext=tier+temperature
Vanilla Furniture Expanded - Farming, for more advanced hydroponics
https://steamcommunity.com/sharedfiles/filedetails/?id=1957158779
Rimefeller, for the ability to produce plasteel and many other useful things
https://steamcommunity.com/sharedfiles/filedetails/?id=1321849735&searchtext=rimefeller
[1.1]Wild Animal Sex V5.0, so you can breed animals after the world ends!
https://steamcommunity.com/sharedfiles/filedetails/?id=1224175982
Trade Ship Drop Spot, so traders never drop stuff where you can't reach it
https://steamcommunity.com/sharedfiles/filedetails/?id=1969732297
Brrr and Phew, to help prevent colonist from wandering out in the cold and dying
https://steamcommunity.com/sharedfiles/filedetails/?id=1707362328
All characters have a 100% chance to start with trait: Undergrounder
Incident(s) disabled:
-Heat wave
-Global warming
-Solar flare
Permanent game condition(s):
-Sun blocked: A nearby sun blocker machine is turning the upper atmosphere opaque, blocking the sun.
Start with:
-Silver x800
-Packaged survival meal x50
-Medicine x30
-Component x30
-Assault rifle
-Autopistol
-Plasteel gladius
-Flak pants x2
-Flak vest x2
-Plasteel flak helmet x2
-Muffalo x4
-Steel x450
-Wood x300
Map is scattered with:
-Ship chunk x3
-Steel x720