Ask HN: Review my Rails/Backbone.js/Facebook Game

Sup y'all,

I made a Guess Who type game using Rails, Backbone.js, and the Facebook SDK. I'd like your feedback on any aspect of the game. I'm specifically interested in how to notify new users that they've been challenged to a game, as well as a better UI for making guesses.

http://www.whoguess.com

Thanks, Michael