Tree path 3 levels King's Pawn Game › Pirc Defense › Rat Defense: Harmonist
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  2. King's Pawn Game B00
  3. Pirc Defense B00
  4. Rat Defense: Harmonist B00 you are here
B00

Rat Defense: Harmonist

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Overview

Rat Defense: Harmonist is a named branch in the Semi-Open Games group of chess theory, classified under ECO B00.

The Semi-Open Games group covers semi-open games — replies to 1.e4 where Black declines the symmetrical 1…e5 in favour of an asymmetric pawn structure.

The line arises from 3 plies — specifically the moves 1. e4 d6 2. f4.

In the opening tree, this line branches off from Pirc Defense, part of the broader King's Pawn Game system.

It continues primarily into one named line, Rat Defense: Fuller Gambit.

Use the board to walk through every move, check how the position has scored on Lichess, or take it head-to-head against Stockfish.

ECO code
B00
Group
Semi-Open Games (B)
Plies
3
Parent
Pirc Defense
Direct variations
1

This overview is generated automatically from the opening's metadata. Know this line well? Write a description — submissions are reviewed before publishing.

Statistics from Lichess

3,352,096 games · White 50.1% / Draw 3.8% / Black 46.1%

MovesGamesW / D / B
Nf61,354,519
g6482,726
e5399,628
c6252,129
e6233,425
Nd7193,592
c5139,758
Nc6113,573

Source: Lichess Opening Explorer · cached 2026-09-26 00:51:52

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Variations (1)