Forcing Moves

Forcing moves are those against which the opponent has limited options, sometimes only one. Non-forcing moves do not limit the opponent's options greatly; they are strategic and can be called quiet moves.
Black to move.
Black can win material with a forcing sequence. 34...Rook-h1-check 35.King-g2 White had one option. 35...Bishop-f3-check 36.Knight-captures-f3 White had three options. 36...Rook-captures-h6 Black is winning.
White to move.

Black to move.
Black and white have many options and can develop how they want. 8...Bishop-d6 9.b4 O-O 10.O-O a6 11.Queen-b3 Queen-e7 Options were never limited, thus the position was not forcing.
White to move.

Tactic

A tactic is when play is forced, as opposed to a strategy which is when play is not forced.
White to move.
White plays a tactic that wins material. 19.Queen-captures-g7 Queen-captures-g7 20.Rook-captures-f6 White is up a pawn; black's queen cannot escape.
Black to move.

Chess is 100% Tactics

Tactics technically assist strategy; thus they are ever present.
White to move.
26.Rook-c6 This move allows white to take over the c-file, an important strategic goal; it is justified through tactics.
White to move.
The idea is 26...Ø 27.Queen-c2
White to move.
If black tries to win a pawn, he loses. 26...Rook-captures-c6 27.d-captures-c6 Queen-captures-c6 28.Queen-d8-check Bishop-f8 29.Bishop-h6 And white wins.
Black to move.
Black to move.
If black tries to win a pawn, he loses. 26...Bishop-e5 27.Bishop-c3 Bishop-b8 28. Queen-d4 f6 29.Bishop-a5 Bishop-d6 30.Queen-c3 White has a winning advantage.
Black to move.

Tactical Puzzle

A tactical puzzle is a position where one can carry out a threat that wins material; or if he is losing, carry out a threat that draws.
White to move.
1.Rook-captures-h6 King-captures-h6 2.Knight-f7-check King-g6 3.Knight-captures-d6 White is winning.
Black to move.

Tactical Position

The more forcing the game becomes, the more tactical the position is.
White to move.
White begins with forceful play and black has no choice but to reciprocate. 12.g5 b4 13.Knight-e2 Knight-e8 14.f4 a5 15.f5 a4 Play is now extremely tactical, i.e. play is forcing.
White to move.
Play continues to be forceful, both sides will have few options on every move. 16.Knight-bd4 e-captures-d4 17.Knight-captures-d4 b3 18.King-b1 b-captures-c2 19.Knight-captures-c2 Bishop-b3 20.a-captures-b3 a-captures-b2 21.Knight-a3 The position has stopped being so tactical.
Black to move.

White to move.
White can play a number of different ways which means the position isn't tactical. 8.Bishop-c6 Bishop-captures-c6 9.Knight-e5 Rook-c8 10.Knight-d2 O-O 11.f4 White wasn't forced to play the way he did.
Black to move.

Finding Tactics

Finding tactics requires calculation skills and the ability to detect when there are threat positions on the board. If one is accustomed to considering forcing moves no matter how unreasonable, he will be able to find tactics consistently. For a player who finds this tiresome, the signals will be an appealing option.
Black to move.
In this world championship game, black blundered because he was unaware there was a tactic on the board; had he been aware, he would've found easily. In the end, he lost the game and the world championship. 26...Knight-captures-e5 Black wins material. For example, 26...Knight-captures-e5 27. Rook-captures-g8 Knight-captures-c4-check King-d3 Knight-b2-check 29.King-d2 Rook-captures-g8 Black is winning.
White to move.
White to move.
Another possibility is 27.Rook-captures-e5 Rook-captures-g4 Black is winning.
White to move.
In short, not being able to detect tactics caused black to miss a golden opportunity and it serves as an advertisement for the tactical signals. However, the signals aren't the only way as considering forcing moves could have helped black find the right move.

Eight Signals

Signals let one know when a tactic might lie in the position. They provide a way of detecting tactics in positions that don't seem outwardly tactical. French chess master and coach, Emmanuel Neiman, invented them and wrote a book about seven signals. Colombian chess master and coach, Daniel Tapia, modified them and added one. They are as follows:

  1. Weak King
  2. Unprotected Piece
  3. Alignment
  4. Constellation
  5. Crucial Defender
  6. Impotent Defense
  7. Trapped Piece
  8. Dangerous Pawn

Signal 1: Weak King

Weak King occurs under the following conditions:

  • A king is exposed
  • A king has few available squares
  • There are many enemy pieces around a king
White to move.
If white plays 21.Queen-captures-d2, he will arrive at the following position.
White to move.
The position is equal. White's two bishops and rook are equal to black's two rooks and knight. White's king is safer and his pawn structure is healthier but black has a passed pawn.
White to move.
However, black's king is exposed and if white plays 21.Bishop-captures-c4, he will arrive at the following position.
Black to move.
White has an advantage. Material is about equal but white's pieces are stronger, his pawns healthier, and his king safer. Compared to Line 1, black does not have a passed pawn.
White to move.
Only with tactical vision can arrive to the superior line. For example, if 21...Bishop-a5 22.Queen-g6-check King-h8 23. Queen-captures-h6-check Knight-h7 24. Bishop-d3 Rook-f7 25.Bishop-e5-check King-g8 26.Bishop-captures-h7-check Rook-captures-h7 27.Queen-g6-check King-f8 28.Queen-captures-h7. Which reaches the following position.
Black to move. White is winning.
White to move.
Another variation from this position is 21...Bishop-a5 22.Queen-g6-check King-h8 23. Queen-captures-h6-check King-g8 24.Bishop-captures-e6+ Rook-f7 25.Queen-g6-check King-h8 26.Bishop-captures-f7. Which reaches the following position.
Black to move. White is winning.

White to move.
Black's king has no available squares. 25.Queen-c6-check b-captures-c6 26.Bishop-a6-checkmate
Checkmate.

White to move.
There are many pieces around black's king. 19.Queen-captures-f6-check King-captures-f6 20.Bishop-e5-check King-g5 21.Bishop-g7. Black's king is surrounded by white's pieces.
Black to move.
21...e5 22.h4-check King-h5 23.Bishop-f3-check Bishop-g4 24.Bishop-captures-g4-checkmate.
Checkmate.

Signal 2: Unprotected Piece

Unprotected piece occurs under the following conditions:

  • A piece is not being protected
  • The signal is multiplied when other signals are present especially weak king
White to move.
There are five unprotected pieces on the board. The signal of unprotected piece is thus very strong. 23.Bishop-f3 White protects his bishop and threatens the d5-rook. 23...Rc5 24.Queen-captures-c1.
Black to move.
White is winning because he has a significant material advantage.

White to move.
Black's king is weak and white take advantage of it. 44.Queen-f7 Qeen-d8 45.Queen-g6 and black resigned.
Black to move.
Black will lose his knight if he defends the checkmate and will get checkmated if he protects his knight.

Signal 3: Alignment

Alignment occurs under the following conditions:

  • Two or more pieces line up on the same file, rank, or diagonal
  • The signal is multiplied when other signals are present
White to move.
Black has a material advantage. There are four pieces on the g-file. Having one's queen in front of his king is usually not optimal, especially when the file is open. 32.Queen-c2 White exploites the alignment and creates a discovered attack on the g7-queen. 32...Ng6 24.f-captures-g6 h6 Black has saved his queen but has lost his material advantage.

White to move.
White has a favorable alignment on the e-file. After 26.Knight-captures-d7 Rook-captures-d7 the signals of alignment, unprotected piece and weak king appear.
White to move.
27.Queen-captures-c6 and white has won a pawn. If 27...Knight-captures-c6 then 28.Rook-captures-e8-checkmate

Signal 4: Constellation

Constellation occurs under the following conditions:

  • Two or more pieces converge on a square that an enemy piece could occupy and attack those pieces
  • It can happen with every piece but it's most commonly associated with the knight
A pawn constellation.
Black's king and rook converge on a square a pawn occupies. If the pawn cannot be taken safely then white will win material.
White to move.
31.Rook-captures-g7-check Rook-captures-g7 32.e-captures-f6-check King-f8 33. f-captures-g7 King-g7 White has a material advantage.
White to move.

A knight constellation.
White's king and queen converge on a square a knight occupies. If the knight cannot be taken safely then black will win material.
Black to play.
40...Knight-f6 41.Knight-captures-e5 Rook-captures-c2 42.Bishop-captures-c2 Queen-a1 White resigned.
White to play.
White cannot move the knight or he will fall to the immediate knight fork. If he plays 43.Queen-g5 Queen-captures-e5-check 44.Queen-captures-e5 Knight-captures-g4-check Black is winning.
A knight fork.
White was unable to escape the knight constellation in the end.

Signal 5: Crucial Defender

Crucial defender occurs under the following conditions:

  • A piece’s defense depends on another
  • A piece is defending two or more squares at once
  • A piece is defending an extremely important square
White to move.
White attacks black's g5-pawn once and black defends it once. That is the essence of crucial defender. Variation A) 25.Bishop-a3 Queen-captures-a3 26.Queen-captures-g5 Rook-e8 27.Queen-captures-h4 Queen-captures-a6 28.c-captures-d5 White has won material.
Black to move.
White to move.
Variation B) 25.Bishop-a3 f-captures-g3 26.Bishop-captures-e7 g-captures-h2-check 27.King-h1 Rook-e8 28.Bishop-d6-check King-a8 5.c-captures-d5 White has won material.

White to move.
White's has a weak king and the e2-Queen and c3-Rook are unprotected. Variation A) 29...Queen-b2 30.Queen-captures-b2 Rook-d1-checkmate
Checkmate.
Black to move.
Variation B) 29...Queen-b2 30. Queen-d3 Queen-a1-check 31.Queen-f1 Queen-captures-c3 The queen could not protect the back rank and the c3-rook.
White to move.

White to move.
Black's c4-Bishop is unprotected, in alignment with g8-King, and is defends the extremely important a6-square.
White to move.
30.Bishop-b3 Bishop-captures-b3 31.a6 c4 32.a7 Black resigned.
Black to move.

Signal 6: Impotent Defense

Impotent defense occurs under the following conditions:

  • Pieces are clumsy or undeveloped; in other words, pieces are not coordinated
  • Pieces are far away from a vulnerability
White to move.
Black's pieces are clumsy and his e8-rook is unprotected.
White to move.
Variation A) 23.Queen-c8 Rook-captures-c8 24.Rook-captures-c8-check Bishop-f8 25.Rook-captures-f8-check King-g7 26.Rook-c8 White is winnning.
White to move.
White to move.
Variation B) 23.Queen-c8 Knight-f6 24.Knight-g4 Rook-be7 25.Bishop-captures-e7 White has won material.
Black to move.

Black to move.
White's pieces are far from the queenside.
Black to move.
26...Knight-a4 27.King-d2 Knight-captures-b2 Black has won material.
White to move.

Signal 7: Trapped Piece

Trapped piece occurs under the following condition:

  • A piece has few available squares
  • Sometimes, the trapped piece cannot be captured immediately
  • Other times, the trapped piece cannot be captured at all
White to move.
Variation A) 26...f4 The e3-Knight must retreat or it gets trapped. 27.Knight-e-captures-g4 h5 The g4-knight is trapped.
White to move.
White's g4-Knight has no squares.
White to move.
Variation A) 26...f4 27.Knight-ed5 c6 The d5-knight is trapped.
White to move.
White's d5-Knight has no squares.

Black to move.
White's e8-knight is trapped but black should not take it now. Variation A) 35...King-captures-e8 36.g4 White will win a bishop because of the alignment.
Black to move.
Black to move.
Variation B) 35...Kd7 36.g4 Bishop-captures-c3 37.g-captures-f5 Bishop-f5 38.h4 Bishop-d3 White cannot protect the e8-knight.
White to move.
39.Rook-a2 King-e8 Black has won material.
White to move.

White to move.
58...g4 59.Rook-captures-h5 King-g7 White's h5-rook is trapped.
White to move.
60.King-captures-g4 Rook-e3 Black is winning; his d6-pawn will promote.
White to move.

Signal 8: Dangerous Pawn

Impotent defense occurs under the following condition:

  • A pawn is close to queening
  • It combines well with the signal of impotency
White to move.
White is down a rook but he has connected passers. White must play carefully. Variation A) 30.d6 Rook-f8 31.Queen-e5 Bishop-c8 Black has the advantage because white's pawns are immobilized.
White to move.
White to move.
Variation B) 30.Rook-f1 Bishop-a6 31.d6 Bishop-captures-c4 32.d7 White's dangerous pawn will recover white's lost material.
White to move.
32...Bishop-captures-f1 33.Bishop-captures-g7-check Queen-captures-g7 34.d8=-Queen-check Rook-captures-d8 35.Queen-captures-d8-check Queen-g8 36.Queen-captures-g8 King-captures-g8 37.King-captures-f1 White is winning.
Black to move.

White to move.
Black suffers from impotency. White's pawns are close to becoming dangerous. Variation A) 33.Bishop-b7 Knight-b7 34.b-captures-a6 Bishop-b8 35.a-captures-b7 King-d7 36.a6 King-c6 37.Bishop-e3 White is winning.
Black to move.
White to move.
Variation B) 33.Bishop-b7 a-captures-b5 34.a6 Bishop-b8 35.c-captures-b5 Knight-b7
White to move.
36.b6 King-d7 37.a7 White is winning.
Black cannot stop the pawns.