I want to do a game where the screen is this maze of crystal facets, and each time you touch one it reflects light differently and reveals parts of a story. Stories. (The Crystal is cracked, all the stories are mazed and multiplied in reflection.) As you progress you find tokens (the flute, the shard, the orrery) that cause more of the crystal to light up. Yes, this is a gimmick but with good artwork it would be intense -- you'd want a 3D space of reflective planes, not just a flat static diagram.
(Late update: the official Dark Crystal website is running some sort of contest to find a tie-in novel author. I suppose I could email them and offer my services as a famous-ish game designer. If I weren't totally behind in all my current game design projects argghh.)