What about some sort of unit or structure editor? You could play around with variables that control what a unit/structure does, and how well it does it. Thinks like attack strength, and concussion or pentration damage, armour, speed?, maximum carrying capacity, or production rate. Does the structure build units or produce some sort of resource, or how much resources it takes to run a building.
There are lots of things to customize in any game. It's always best if you can avoid hardcoding stuff. Plus, it makes it easier for you if you just get a bunch of content creators to fill in details, or fine tune things for you. It leaves more time for you to work on the rest of the project, or just set rough values and let someone else work out the details.