Retrograde Analysis

Do we have passionnate people about it?

I made an introduction video there: https://www.youtube.com/watch?v=PGPw8n0LqPc&t

In the end of the video you'll find a personnal puzzle, tell me in the comments if you solved it (-;
(Yes there is a trap)

Nice Florian, I loved Raymond Smullyan's books despite headaches...
For the problem on the 1st book's cover, you did not explain why it could not be a pawn's promotion, is it because of certains conventions on board orientation?

Yes, bottom is always the white side, except if you make a "puzzle joke" :D

For your problem, do you ask for shorter mate, cause I can find several?
How can we post here without spoiling?

Of course, shorter one. You can post on the YouTube directly if you want no problem.