For the first time ever I did visit the HD Hint House and how interesting it was!

To start with, it was much larger than the original tutorial and I did miss 25 % of the secrets ...
:-[

I especially could appreciate the sign that gave information about the boards and the way of communicate about rooms with the help of the Command+D buttons.

Also the message that keys replace shields in a full inventory is major information for new players.

Edit: a revisit gave me exact the same bad result, but the good news is that I know now that 25 % means 3 secrets.