The qualities of chess consists mainly of a special role of the king. If a check is declared, the very first thing needed is to defend the king. At the same time, another piece can be attacked without excess consequences or counterattack. If there is no way to save the king from a check, then the game is over and it doesn't matter if either side had a better position. The special role of a king is best shown in the case of a stalemate, a perpetual check, or whatever.
Paul Keres
White to move and mate in four:
We'll take a look at some examples. In Paul Keres' composition (above) black has the material advantage but white is expected to win because Black's king is weakly placed: 1.Bg5! Rf7 2.Bf4 Nc6 3.Bd2 and whatever move black makes will simply lead to 4.Bc3#, mate.White to move and draw:
In diagram #2 (above) white has three extra pawns but fortunately black is provided with a stalemate: 1.f6 Bxf6! 2.Kxf6=, stalemate.Shamkovich - A. Polyak
Leningrad, 1953
White to move and win (mate in two):
In the game Shamkovich - Polyak (above), it seems that black would have the advantage because of the passed pawns. Surprisingly though, white can deliver a checkmate in two: 1.Qxh6+ Kxh6 (or 1... Kg8 which leads to a mate by White's f-pawn with 2.f7# mate) 2.Rh3#.During a castling attack it is often necessary to sacrifice pieces or pawns with the purpose to break down your opponent's pawn protection. Let's take the game Batuev - Abdusamatov for an example (diagram below). It is white to move and win: 1.Bxh7+ Kxh7 (or if 1...Kf8 then 2.Bh6!) 2.Bf6! Bxf6 (if the pawn captures the bishop with 2...gxf6, then white simply plays 3.Re3 and everything is downhill for black) 3.exf6.
Batuev - Abdusamatov
USSR, 1951
White to move and win:
In the position showed in diagram #5 (below) black had to force some exchanges in order to make the best of his weary position: 1...Rxf5 (or else a mate is enabled with 1...Bxg2 2.Ne7+ Kh8 3.Qxh7+!) 2.Rxf5 Qxe3+ 3.Kh1 Bxg2+ 4.Qxg2 Rae8 5.Qd5+ Kh8 6.Rf3, and in several moves white won the game.Kan - Abramowski
Leningrad, 1951
Can black play 1...Bxg2?:
Another important quality of a chess game is that of a pawn; it is able to promote to any piece, except for a king, of course. Let's take a look at diagram #6 (below): 1.Qg7! and black resigned because either way if 1...Rf8 2.Nf6+ or 1...Rxg7 2.hxg7.White to move and win:
In this next chess problem (diagram #7) we will quickly study a pawn endgame breakthrough technique: 1.b6! axb6 2.a6! Bb8 3.a7! Bxa7 4.c7 and in one move a queen promotion with 5.c8=Q.Diagram #7
White to move and win:
In the last study of this post, we will look at the end of a game that was played by Samuel Reshevsky and Isaac Boleslavsky (diagram #8). The last move played was 1.R3d7? (the correct move was to play 1.Rd8), and now black had the opportunity to get away with a draw by playing 1...Ra7! with the idea of distracting the rook and promoting his own pawn. Interestingly though, both players missed this line.Reshevsky - Boleslavsky
Zurich, 1953
Black to move and draw:



