Fulgora's moon of puzzles. Ancient wrecks embedded in thick ice can seemingly be repaired, including a colossal nuclear reactor that could transform the possibilities on the surface... if you can get it working. Cerys is a complete and polished mod that does not modify the vanilla game in any way, so is easy to include in existing saves.
Mods introducing new content into the game.
For fast response to bug reports (and to talk with other players) you are welcome to use Discord.