You have been imprisoned by your super duper cliché evil king named Tim Goldsteen for sneezing during his birthday party. Apparently he’s that evil. Anyhow, you found out Tim’s secret that he enjoys chess and is a grandmaster. However you did that in jail. Not wanting his secret revealed, as the Chess Players Against Evil Grandmasters Society (WHY does that exist? I’m gonna kill whoever wrote this script for me!) was after him, Mr. Goldsteen came up with an idea.
Instead of reasonably stabbing you in the face or something right then and there, he offers to spare your life if you keep his secret. But first you must complete a challenge.
He tasks you with creating a game with the following conditions:
- It is white to move and checkmate
- Black must have 10 knights in the starting position. Your starting position is to be constructed by you.
- All of black’s moves must be knight moves. The black king cannot move at all, i.e. because it cannot, ever.
- All of black’s moves are forced, but variations are allowed to occur.
- At least 9 of the black knights must move. (I say this because this is the limit that I ran into. I congratulate you if you can get all ten!)
- The black king can be the only black piece left at the end of the game.
- It must be legal.
- FIDE laws of chess apply.
- Assume that black is playing optimally.
- I may or may not already have a solution.
You have 24 hours to complete the task before he comes back and stabs you in the face or something like he should have done earlier. He manically laughts as he slowly walks off to eat his dinner of turkey fries.
“Call it a not so knights challenge!” Tim Goldsteen yelled before he vanished from your range of hearing.
P.S. If you don’t understand what “variations are allowed to occur" means, see my answer to this CSE question: https://chess.stackexchange.com/questions/4963/longest-sequence-of-mutually-forced-moves/24148#24148
Basically, black must, by the laws of chess aka forced moves, take the checking white piece, but he has a few options on how to do so. All of his options are forced, no matter what route he takes.
EDIT: Seeing as Arnaud Mortier's answer is actually invalid, this is still an open question.
EDIT #2: Now they actually have solved it!