r1bqkr2/2ppppbp/n6n/1p6/4P1p1/2pK2PN/PB1PBP1P/RN2Q2R b q - 0 13
FEN state: r1bqkr2/2ppppbp/n6n/1p6/4P1p1/2pK2PN/PB1PBP1P/RN2Q2R b q - 0 13 ; Best move: a6b4
The current state of the chess board is: Black rook at a8, black bishop at c8, black queen at d8, black king at e8 and black rook at f8. Black pawn at c7, black pawn at d7, black pawn at e7, black pawn at f7, black bishop at g7 and black pawn at h7. Black knight at a6 and black knight at h6. Black pawn at b5. White pawn at e4 and black pawn at g4. Black pawn at c3, white king at d3, white pawn at g3 and white knight at h3. White pawn at a2, white bishop at b2, white pawn at d2, white bishop at e2, white pawn at f2 and white pawn at h2. White rook at a1, white knight at b1, white queen at e1 and white rook at h1. Black queenside is the only castle move available. Half move number is 0. Full move number is 13. Black to move.