As far as I can calculate, 6 is the limit for the most number of pawns on a single file possible. Is 7 possible at all, ignoring promotion? I only took into account using the edge of the board, not the center, so I may be wrong. If I am right, what are some ways to make my composed game go quicker?

The composed game is below. It is 50.5 moves long.

[FEN ""]
1.Nc3 h5 Nb1 g5 Nc3 f5 Nb1 e5 Nc3 d5 Nb1 c5 Nc3 b5 Nb1 a5 Nc3 h4 Nb1 h3 gxh3 g4 Nc3 g3 fxg3 Qh4 gxh4 f4 Nb1 f3 exf3 Bg4 fxg4 Rh5 gxh5 e4 Nc3 e3 dxe3 Bd6 Nb1 Bf4 exf4 Nf6 Nc3 Nh7 Nb1 Ng5 fxg5 Nd7 Nc3 O-O-O Nb1 Rh8 Nc3 Rh6 gxh6 d4 Nb1 d3 cxd3 Nf6 Nc3 Ne4 dxe4 b4 a4 bxa3 Nd5 axb2 Ne3 b1=Q Ng2 c4 Ne3 Qb5 Bd2 Qf5 exf5 c3 Qe2 c2 Rb1 c1=Q Qd1 Qc6 Rb7 Qg6 fxg6 a4 Rb6 a3 Rb5 a2 Rb4 a1=Q Rb3 Qa7 Rb4 Qh7 gxh7
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    If you don't count pawns on promotion squares (last row), then obviously you can only have pawns on the second to seventh row, I.e. max six pawns on a file. – user1583209 Feb 25 '19 at 6:28
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    If you do allow pawns on promotion squares, you need 6+10=16 captures, which is impossible. – user1583209 Feb 25 '19 at 6:33
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    To get to the same file, with minimum number of captures you need pawns from three files on one side and four files on the other side. Those are 1+2+3 =6 captures from one side and 1+2+3+4=10 captures from the other side. – user1583209 Feb 25 '19 at 7:07
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    oops. Indeed you only need 6+6=12 captures (three pawns from the left, three from the right), because you already have one pawn on that file... – user1583209 Feb 25 '19 at 14:27

If you only include legal positions then 6 is the limit. The pawns could possibly occupy the 2nd-7th ranks, via diagonal captures towards the desired file.

If you ignore promotion and allow pawns to be on the 8th rank (or 1st rank for Black's POV) then the limit is 7.


Using black pawns, mamy thanks to @DM for this idea, I have completed my quest to find the perfect 7-same-file pawn proof game. I used black to shave off half a move.

[FEN ""]
1. d4 b6 2. d5 a5 3. d6 exd6 4. Qd5 c6 5. e4 cxd5 6. b4 f5 7. Bd3 fxe4 8. c4 exd3 9. c5 bxc5 10. Be3 axb4 11. Nc3 bxc3 12. Bd4 cxd4 13. O-O-O g5 14. f4 gxf4 15. Rd2 cxd2+ 16. Kb1 f3 17. Ne2 fxe2 18. Rd1 exd1

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