Transportation of the player, be it vehicles or teleporters.

Augmented or new ways of transporting materials - belts, inserters, pipes!

Trains are great, but what if they could do even more?

New ways to deal with enemies, be it attack or defense.

Armors or armor equipment.

Changes to enemies or entirely new enemies to deal with.

New Ores and resources as well as machines.

Things related to oil and other fluids.

Furnaces, assembling machines, production chains.

New places to build more factories.