You cannot castle in chess if the king or the relevant rook has moved, if there are pieces between them, if the king is currently in check, or if the king would move through or land on a square that is attacked by an enemy piece. Castling is a special move requiring specific conditions to be met, primarily related to king safety and piece movement history.
Castling is permitted only if neither the king nor the rook has previously moved; the squares between the king and the rook are vacant; and the king does not leave, cross over, or finish on a square attacked by an enemy piece. Castling is the only move in chess in which two pieces are moved at once.
You can't castle if you have ever moved your King (not even if you moved it back later) or the Rook you want to castle with; or if you are in check, or would be castling across a check or into a check. Enemy attacks on the Rook don't matter... you ARE allowed to castle even if the Rook is under attack.
Though castling often looks like an appealing escape, you can't castle while you are in check! Once you are out of check, you can castle. Being checked does not remove the ability to castle later.
There is no 15 move rule in standard chess. Gomer_Pyle wrote: I looked at some of your games but didn't see one that fit your description. I found a game with 35 moves without a pawn move or piece taken but not one with 50 moves.
The four main rules for castling in chess are: neither the king nor the chosen rook can have moved; there must be no pieces between them; the king cannot be in check; and the king cannot pass through or land on a square that is attacked (i.e., cannot castle out of, through, or into check).
The 3-check rule in chess is a popular variant where you win by putting your opponent's king in check three times, in addition to the standard win by checkmate; the game uses normal chess rules but adds this new victory condition, meaning players must track the number of checks given and received, as a third check ends the game immediately, even if checkmate hasn't occurred. A double check counts as a single check towards the total, and you cannot deliver the third check while your own king is in check.
Castling too early also loses you a timing a development. I usually castle after move 10 or so, when the knights and at least one bishop are out and I don't have a good attack going. I sometimes use the gained timing to put some pressure if possible, maybe even start to push the pawns on the opponent's castling side.
The 20-40-40 rule in chess is a study guideline for improving players, suggesting you allocate your study time as: 20% on openings, 40% on the middlegame (tactics and strategy), and 40% on the endgame, emphasizing that understanding middlegame plans and endgame technique is crucial for converting advantages, not just memorizing opening lines. It's particularly useful for players below the 2000 rating level to build a balanced foundation.
If you touch the rook first, you must instead move the rook instead of castling! By moving its king (Rule 1), Black has forfeited its castling rights, while Black's bishop on a6 prevents White from castling through a checked square (Rule 3).
An illegal move is any move that violates the Laws of Chess—e.g., moving a piece in a way it cannot move, castling through/into check, leaving your king in check, promoting a pawn incorrectly, pressing the clock without making a move, or using two hands for a single move (such as castling or promotion).
The rarest checkmate in chess, mathematically, is the Doubly Disambiguated Bishop Capture Checkmate, requiring three bishops of the same color to capture a single piece for mate, with odds less than 1 in 342 billion; no recorded instances exist, though a similar bishop-queen discovery mate was noted. Other extremely rare mates include castling mates, knight underpromotion mates, and the "Reset Checkmate," but they pale in rarity compared to the triple-bishop scenario.
The 3 Cs of chess strategy usually pertain to controlling the center, castling, and connecting the rooks. Some chess coaches, however, have used the 3 Cs for other chess principles such as 'choice, commitment, and consequences'!
Here, white cannot castle to his queenside because the king would have to move over square 'd1' (where the red 'X' is) on its way to 'c1'. Square 'd1' is covered by the black bishop on 'g4'. (Follow the arrows from the black bishop on g4 to the 'X' on 'd1'.)
