I spent these last days building a spreadsheet app for managing resources in a city builder / survival sim (Medieval Dynasty). I'm pretty sure there are plenty of ways to improve it, I know that other people have already built solutions for it that I could have used instead and I know that a much better solution would involve a proper database.

But it was fun, dammit. I need to deal with spreadsheets for work and it was a fun effective way of honing my skills with them.