As games crossed over from niche pasttime to mainstream success, more and more world-class artists have lent their vision to the pursuit of digital leisure. Stephen Spielberg has put his fingers in many a game-pie, from 1995's PC adventure The Dig to the unrealised project for EA, codenamed LMNO. Composer Philip Glass contributed a song to Chime, a rhythm puzzle game whose proceeds went to charity.

But where is the final level fortress designed by I.M. Pei?