# Copycat Chess (Part 3/3)

After finishing the mating move in the second game, Li Chai looked at the mandarin and asked:

What do you say now?

1. d4 d5 2. e4 e5 3. dxe5 dxe4 4. Bg5 Bg4 5. Qxd8#

It's not much of an achievement if you take my mating piece. After all you started the game and you have an advantage.

Li Chai stayed calm again and started the final game.

How did Li Chai win the third and final game?

The rules (same as in part 1):

• standard chess rules apply, if not stated otherwise
• you play white and your opponent copies all your moves (e.g 1. e4 would be followed by 1. ... e5)
• you are allowed to make "stupid" moves, your opponent will copy all moves regardless how bad they are
• you are not allowed to make moves which cannot be copied, of course except for the last move winning the game

New rule:

• make it impossible for the mandarin to repeat the mating move, but without taking the corresponding black mating piece
• So you can take a black piece on your last move, you just can't take the piece your opponent is supposed to use to copy your last move? – klm123 Apr 9 '16 at 13:08
• @klm123 Exactly. – Sleafar Apr 9 '16 at 13:09
• This could probably also be posted on the Chess Stack Exchange. – Mr Pie Jul 2 '18 at 3:17
• @user477343 AFAIK posting the same question on different SE sites isn't considered a good practice. – Sleafar Jul 2 '18 at 4:21

The final position:

The moves:
1. Nf3 Nf6 2. Nd4 Nd5 3. Nc6 Nc3 4. dxc3 dxc6 5. h4 h5 6. Rh3 Rh6 7. e4 e5 8. Bd3 Bd6 9. Kd2 Kd7 10. Re3 Re6 11. Be2 Be7 12. Kd3 Kd6 13. Kc4# *

• Nice idea and within the rules, but there is another possibility which makes use of a rather obscure chess rule and needs only 13 moves. Can you find it? – Sleafar Apr 9 '16 at 14:10
• I'm thinking the obscure rule might be en passant, but at that point Kao Tse might think Li Chai was just making the rules up. – f'' Apr 9 '16 at 14:29
• It's not the intended solution, but I think it's valid. I'll post the solution from the original story in a separate answer. – Sleafar Apr 9 '16 at 15:41
• The question asks for a mate such that black cannot repeat the mating move. Here black could play Kc5. This is of course illegal because black is moving into check, but even in Part 1 black's option of repeating white's move leaves the black king in check. – Julian Rosen Apr 9 '16 at 21:52
• @JulianRosen I wasn't aware there were other methods to solve this than the intended one. The reason I accepted this is: 1) the black king is mated 2) he cannot mate the white king by repeating the move 3) the mating piece is not taken. The previous solution found by klm123 was probably even more convincing but way longer. – Sleafar Apr 10 '16 at 6:00

@klm123 found a way to beat the mandarin again. However Li Chai used a different method in the original story.

Preparation:

1. e4 e5 2. g3 g6 3. Ke2 Ke7 4. Kf3 Kf6 5. Kg2 Kg7 6. c3 c6 7. Qb3 Qb6 8. d4 d5 9. dxe5 dxe4 10. Bg5 Bg4 11. Ne2 Ne7

Finale:

12. f4 f5 13. exf6#

In the last move the black pawn is taken according to the en passant rule. This is only allowed in the move directly after the pawn to be taken has moved 2 squares forward. Therefore black cannot repeat this move.

• Nice! This breaks the chain. – Joshua Apr 10 '16 at 0:37

When I showed this puzzle to my friend he found a solution in 10 moves. I think it should be here for the sake of completeness.

The final position:

The moves:

1. d3 d6 2. Kd2 Kd7 3. Kc3 Kc6 4. Kb3 Kb6 5. Ka3 Ka6 6. Nc3 Nc6 7. Nd5 Nd4 8. Nb6 Nb3 9. axb3 axb6 10. Kb4# *

An improvement of @kim123's answer. Using Bc1 instead of Nb1 is one move faster. (White's move 9)

1. d3 d6 2. Kd2 Kd7 3. Kc3 Kc6 4. Kb3 Kb6 5. Ka3 Ka6
6. Be3 Be6 7. Bb6 Bb3 8. axb3 axb6 9. Kb4#

• Welcome to Puzzling! I think this does count as an answer in itself; it's fine to use existing answers as a basis for your own one, especially if you mention where your inspiration is coming from. – Glorfindel Jul 1 '18 at 16:44