I'm putting this up because the is the first time I learnt how important version control is. I was making this and after about a weeks worth of effort - remember, no git, no manual drive backup, I accidentally spilled water over my laptop. I had to have the hard-disk replaced and there was no way to retrieve it. Sigh - I struggled for about a week to recover the source code by decompiling the debug apk I had in my phone, renaming things and making the app work again. Very painful! The idea to make this however came up because as a child, my father used to quiz me on cities and capitals all the time but I'd always struggle to remember our world map. Part learning, part childhood memory!