I think I didn't so much learn new things so much as I got an applied perspective on things that I had already learned. It's one thing to read about value added in a textbook, it's another thing to actually experience it in person buying reagents and selling potions in WoW. You can read about the benefit of fuel transferring lifting stages (aka "asparagus staging") in an article it's another thing to reach that design in KSP, and understand why SpaceX tried to do it.