"Ender's Game" has long been one of my favourite works of SF, and I think this may have surpassed it; according to the introduction, it was what the author was trying to write when he came up with "Ender's Game". As with Card's other work, it's the strong outsider characters and extremely inventive settings that make this interesting -- this one has strong detective-story elements too, which Card pulls off in an elegant and satisfying way. Using "ramen" as the plural of "raman" was a bit disconcerting, though! Highly recommended.
ISBN 1857238575.