Almost no real surface has been left intact after Calidus imploded. Start on a small immobile station, build ships to harvest what's left of the solar system and explore factorio through a new tech progression
Large total conversion mods.
New places to build more factories.
Augmented or new ways of transporting materials - belts, inserters, pipes!
New ways to deal with enemies, be it attack or defense.
Changes to enemies or entirely new enemies to deal with.
Map generation and terrain modification.
New Ores and resources as well as machines.
Furnaces, assembling machines, production chains.
More than just chests.