It took me nearly 30 hours of playing time, Gerry, to get through it all. Rhem 2
took me at least 10 hours longer because of the maze with the glass walls.
The Rhem games are difficult but wonderful puzzlers. As you play, you learn that the clues to every puzzle are there for the looking, but you have to be very observant and take really good notes. I walked around for the longest time in one section before thinking to look up, and I've learned how important the reverse side of doors and hatches can be. Having a decent sense of direction and a good map helps, too.