Click on the third or sixth rank to set the en passant target square.

Book: 118 / 633

# move proof disproof
1 Rf1 87 118
2 Rg1 60 152
3 e4 38 277
4 Nc3 29 355
5 Kd1 31 357
6 h4 38 374
7 f3 18 402
8 g3 35 403
9 Na3 32 424
10 d3 24 444
11 a4 29 450
12 b3 34 454
13 Ke2 28 454
14 h3 19 455
15 c4 31 480
16 Kf1 27 511
17 a3 18 523
18 c3 19 564
19 f4 17 567
20 b4 19 633
21 d4 0