I'd love a mod that actually respected the true materials/engineering recipes in real life.
Obviously, you can't recreate the complete complexity of all global supply chains, but it would be nice for a mod to get a little closer.
Standard factorio glosses over way too much to be considered educational, which is what i need before I get my son addicted with me. (Yes, i know standard Factorio still has a lot to offer - i just want more detail)