Hmm. For some reason Shift just doesn't DO it for me. You can't really solve the puzzles before you start moving about the screen, since you don't know how different locks and keys will work before you do, and when you do start to try stuff out the puzzles pretty much solve themselves. There's nothing BAD about these games, tho.
I only played this through for the badges but I'm kind of enjoying trying to clear it in 18 days or less. The fact that a single mistake means you have to return to the beginning is rubbish but hasn't quite stopped me from plugging away at it.