The factory must grow, but only if you have the proper permits. Replace biters with complainers and weapons with bureaucracy.
Large total conversion mods.
Transportation of the player, be it vehicles or teleporters.
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.
New Ores and resources as well as machines.
Related to roboports and logistic robots.
Furnaces, assembling machines, production chains.