r2qkb1r/1pp1pp2/3p1n2/6Np/pPb1P1p1/8/P1Q1nPPP/RNB1KBR1 b Q - 1 21
FEN state: r2qkb1r/1pp1pp2/3p1n2/6Np/pPb1P1p1/8/P1Q1nPPP/RNB1KBR1 b Q - 1 21 ; Best move: c4d3
The current state of the chess board is: Black rook at a8, black queen at d8, black king at e8, black bishop at f8 and black rook at h8. Black pawn at b7, black pawn at c7, black pawn at e7 and black pawn at f7. Black pawn at d6 and black knight at f6. White knight at g5 and black pawn at h5. Black pawn at a4, white pawn at b4, black bishop at c4, white pawn at e4 and black pawn at g4. White pawn at a2, white queen at c2, black knight at e2, white pawn at f2, white pawn at g2 and white pawn at h2. White rook at a1, white knight at b1, white bishop at c1, white king at e1, white bishop at f1 and white rook at g1. White queenside is the only castle move available. Half move number is 1. Full move number is 21. Black to move.