I've only realised recently that you use the shift key to "shift" your perspective (I can be quite slow sometimes).
While I never loved this series, playing recently, I gotta say: this game still holds up! The music is short but not annoying, the puzzles are easy but cool to solve (and it feels like you had fun with the last levels and that's great), the controls are quite smooth for an old game and the mechanism is very original! and the minimalistic graphics complements it very well!
Overall it's a very good game, bravo.