How many puzzles are there? I have 37 in my puzzle free-play, but one review I read said that there are over 50.
The hardest puzzle for me was the room key puzzle. I used all hints and still had three submissions. I was trying different variations of binary until I looked at the hints, at which point I tried to make tally marks pictograms out of the squiggles. The other puzzles are all nines and tens!