The Cuttlefish Engine was a game creation package that let you easily create games for iOS and Android. You'd write your games using a combination of a graphical editor (think Kismet or GameMaker), and some C# code for the difficult bits, and the engine would spit out apps for Android, iOS, PC, and Windows Phone. It was a fun project but way too ambitious - I was trying to compete against engines like Unity or Unreal, except I had significantly less resources. So yeah - still some of the most interesting code I've written to date.... one of these days I'll get around to posting more information about it and stuff.