There's traditional "Metroidvania" item collecting, shooting, and puzzle-solving, but the tilting camera, the somber soundtrack and a few neat audio tricks make this game worth a taste. There's also a guiding voice, a la Portal's GlaDOS, that will help you through the multi-room adventure. K.O.L.M., by Antony Lavelle with music from Tommy Robin, has been out and playable for a little while now, but thanks to Rock Paper Shotgun, we're now better aware of its existence.
If you've got some time to spare for this Flash-based adventure, give it some time.
EDIT: I know we had this game as a LunchTimeWaster – I just thought, 'let's give more attention to this awesome flash game'!