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

Book: ∞ / 0

# move proof disproof
1 f4 0
2 c6 0
3 Kd6 0
4 Na6 0
5 Nc6 0
6 Ke7 0
7 Kd8 0
8 Ke8 0
9 c5 0
10 Ba6 0
11 Kc6 0
12 Ke6 0
13 a6 0
14 a5 0
15 Bb7 0