What I like about the 'Underworld' thing is that it's a mix of cool genres, as well as creating its own message.
Whenever I finish a book, I start with a blank slate and never have ideas lined up.
We decided to play the NEC because we were asked to, and because we actually rather like the place: we've always enjoyed doing it before. We don't often get sensible offers to play in the UK, so most years we just play on the mainland, with the occasional exotic detour.