How many unique checkmates are there from this starting position?

I can only see 5 lines on lichess from a game I've played and have tried several different moves.

Mate in 4 is the fastest but I've seen up to 12. There must be at least 15 different mates, not all of them have the same ending position.

[Title "Black to move"]
[fen "8/p2rk3/1pQ1p1p1/2p5/1P2P3/2PP1n2/P2bq3/RK1R4 b - - 0 1"]
  • 5
    Practically infinite. Take the rook and trade off material, then keep shuffling your pieces indefinitely.
    – shawn_xu
    Aug 10, 2023 at 21:11
  • @shawn_xu there is still a limit to how long a chess game can go on, 50 moves without capture are considered to be a draw. Aug 10, 2023 at 21:38
  • Still one side has to claim a draw before the game officially ends.
    – shawn_xu
    Aug 26, 2023 at 2:15
  • You're asking for the number of ending positions and not the number of first moves by Black that will lead to checkmate, right? If it's the number of ending positions, are we assuming White is cooperating with the final position? Like, 1...Bxc3 threatens Qb2# but White can choose to not defend the mate and play something weird like Rh1 just so the ending position is different than what you're aiming for (or to create a different ending position that you are aiming for.)
    – D M
    Jan 1 at 17:26


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