Amazing! Its really good to find games that I haven't heard about before. I'm yet to play through most of the suggestions, but I'm looking forward to it.
Perhaps I managed to mislead myself by asking specifically for "puzzle games" (after all, the focus is on the variety that the indie world has to offer). Perhaps I should have said "games that don't take more than 20 seconds to get into" as this is actually the big limiting factor here. That would (in my mind) exclude any really long FPS/RPG's or games that start with a long pre-amble/story, but leave most other things open. The "re-evaluating assumptions" criteria is also key.
I'm sure I'm not just saying this because I saw Proteus (
http://www.visitproteus.com/) on my searches yesterday and I really REALLY want to include it in the expo.
Thanks for the suggestions, I'm going to see how many I can play in the next 2 hours.