I think it is mentioned:

If a letter is guessed that does not appear in the puzzle, or that has already been guessed or revealed, then that counts as a strike.

Sample test still uses old classifications naming.

To match the description, 'N' should be 'C1', 'M' should be 'D1'.

Fun, some basic numeracy :)

I think I managed to pass by overflowing the buffer, huh

Tests in Python could use some improvements. They are structured quite poorly, no good distinction into test groups, fixed tests, random tests, etc.

It is not specified what should happen if the same character is guessed again.

Initial code is invalid: it should be self.secret instead of Hangman.secret, etc. They should not be class variables.

Done

Could use tags: Probability, Combinatorics

This kata blew my mind. 5 stars

I've expanded the description if it helps. It feels too elaborate, so you're welcome to trim it down.

Fixed