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

Book: 319 / 4198

# move proof disproof
1 c4 50 319
2 b4 40 319
3 f4 21 319
4 a4 23 322
5 Nf3 43 327
6 g4 40 329
7 f3 56 331
8 h4 21 335
9 g3 312 905
10 b3 307 987
11 Nh3 274 990
12 c3 259 1093
13 Na3 222 1177
14 h3 241 1179
15 Nc3 196 1244
16 a3 165 1406
17 e3 1928 1972
18 d4 0
19 d3 0
20 e4 0