r1q1kb2/1b1p3r/1pn3p1/p1p1pp1p/3PB2P/NP2PP2/n1PK1QP1/R5NR w q - 0 21
FEN state: r1q1kb2/1b1p3r/1pn3p1/p1p1pp1p/3PB2P/NP2PP2/n1PK1QP1/R5NR w q - 0 21 ; Best move: d4d5
The current state of the chess board is: Black rook at a8, black queen at c8, black king at e8 and black bishop at f8. Black bishop at b7, black pawn at d7 and black rook at h7. Black pawn at b6, black knight at c6 and black pawn at g6. Black pawn at a5, black pawn at c5, black pawn at e5, black pawn at f5 and black pawn at h5. White pawn at d4, white bishop at e4 and white pawn at h4. White knight at a3, white pawn at b3, white pawn at e3 and white pawn at f3. Black knight at a2, white pawn at c2, white king at d2, white queen at f2 and white pawn at g2. White rook at a1, white knight at g1 and white rook at h1. Black queenside is the only castle move available. Half move number is 0. Full move number is 21. White to move.