Notice how the Rook on the second rank controls (or looks at) all of the squares on the second rank? It looks at the squares a2, b2, c2, d2, e2, f2, and at the square h2. All because this Rook sits on the g2 square.
Rooks move along Ranks and Files so our Rook from up above also looks at all of the squares going up along the g-file. That is from the bottom of the board up to the top of the board. If a piece looks at a square then it is attacking that square and any opponent's piece moving onto that square can be captured.
Remember the number one rule of chess - A King can never step onto a square that is attacked. We can never leave our King in check nor can we step onto a square where we - that is our King - will receive a check.
If our King is in check we have a list of possible options that we need to check in order to make sure that we are not in checkmate. This is the list and you should always check it in this order:
1.) Can our King (or another one of our Pieces) capture the piece looking at our King - the piece giving check.
2.) Can we use one of our other pieces to block the check? That is can someone else take the check for the King.*
3.) Can our King run away to a square around him to escape from the check?
*Remember that a Knight giving a King check is the one kind of check that the King cannot block. So when a Knight gives our King a check he must either have some other piece capture the Knight or our King must run away.
If we cannot capture, block or run away - then we have been checkmated.
The move King from g1 to h2 is the winning move for Black in the above diagram! Congratulations to all of our players who found this move.
Kh2 won the game because once the Black King got out of the way of the Black Rook he allowed the Rook on h1 to stare at the White King on b1. Because the Black King went to h2 - as opposed to the square f2 - he did not block the view of the other Rook along the 2nd Rank.
The reason why this is a CHECKMATE is because:
1.) The player of the White pieces is unable to capture the Rook on h1. He only has a King left in the game and the King can only move one square at a time.*
*Unless we use the special moves "CASTLES".
2.) No other piece can land on any of the squares between the White King and the Black Rook on h1 to BLOCK the check.
3.) The White King cannot step up onto the 2nd rank as the other Rook, the one on g2, looks at all of the squares on the second rank.
So this is a checkmate! Game over - we can set up all of the pieces to the start position now and start a new game!
- Chess Coach Sean Tobin.