The following idea is lifted directly from one of the great teachers of amateur chess around, Dan Heisman. While most all games are decided by tactics, not every position has a combination hidden in it. Even if a player gets good at tactics puzzles, finding those patterns in real time in an actual game is where the payoff comes. A player needs to know when it's worth extra time looking for tactical shots. Heisman came up with the Seeds of Tactical Destruction to make that bridge.
Directly from the horse's mouth:
You should be careful about creating/having the following –
and if your opponent has them, Look for a Tactic!:
·Weak Back Rank
·Pinned or “skewerable” Pieces along the same rank, file, or diagonal
·Overworked Pieces (Pieces guarding more than one piece or square)
·Inadequately Guarded Pieces
·Falling Way Behind in Development (overwhelming opponent forces)
·Opponent’s pawns nearing promotion
·King uncastled or lost pawn protection with Queens on the board
·Open enemy lines for Rooks, Queens, and Bishops to your King
·Pieces that have little mobility and might easily be trapped if attacked
·One or More Pieces than Can be Attacked via a "Discovered" Attack"
I have always considered this list to be a little long. As such, I use the idea extensively when I teach, but summarize to the following 4 ideas.
King Safety
Unguarded (or Underguarded) pieces
Lines (Open or vulnerable)
Differences in Development
The added bonus to this list is that is not much different from the elements of POSITIONAL evaluation:
King Safety
Pawn Structure
Development
Open Lines
Best Squares
In fact, pawn structure can be a clue to a tactic as well, showing how closely positional and tactical ideas can be.
White to Play:
In this position, the seeds of tactical destruction might look like this:
1. King Safety: Black has castled and is in the corner but has many open diagonals which white can use.
2. Unguarded pieces: the rook on f8 is unguarded, as is the queen on c7.
3. Lines: the knight on c6 is pinned (Pins are one of the most important basic tactics that come from vulnerable lines)
4. Development - essentially equal. Neither side has advanced further into the other's territory, or has a majority of their weapons pointed in one area.
Based on these elements (thinking about the pin on c6, and the open lines point at the king), the move Bd4 becomes a candidate. The move is checkmate, save for two defenses: the pointless block Rf6, and the recapture Nxd4. Therefore, Nd4 is forced. Unfortunately, due to the vulnerable line, white eats the queen.
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