Kasparov’s Insight: Chess VS Shogi ,Why Shogi’s "Drop Rule" Changes Everything — A Shogi 4-Dan Analysis

 Summary

• Chess requires deeper calculation in the endgame.

• In shogi, it is often sufficient to calculate only near-terminal positions, but players must consider a much wider range of branches.

Introduction

There was a time when the famous chess grandmaster Garry Kimovich Kasparov(Га́рри Ки́мович Каспа́ров) played shogi.

During a shogi-related event in Japan, he commented on the differences between chess and shogi, noting that the ability to reuse captured pieces is a unique feature of shogi.

In this article, I will explain why piece reuse is such a distinctive characteristic, based on a comparison of the fundamental features of chess and shogi.

Differences in the Endgame Between Shogi and Chess

Chess requires deeper calculation in the endgame.

In contrast, shogi involves a much higher number of branching possibilities, and compared to chess, players can only realistically calculate positions that are close to checkmate.

This difference stems from how captured pieces are treated in each game.

In chess, captured pieces are permanently removed from the game and cannot be reused. As the game progresses into the endgame, the total number of pieces decreases, which in turn reduces the number of possible patterns and branches, making calculation easier.

In shogi, however, captured pieces can be reused at any time.

As a result, no pieces are ever completely removed from the game. This means that even in the endgame, the number of possible branches does not decrease. Players must continue to consider a wide range of possibilities until the very end.

Given the limits of human calculation ability, this likely explains why chess players tend to calculate deeply from earlier positions, while shogi players focus on broad but shallow calculation immediately before decisive moments.

Differences in the Opening Between Shogi and Chess

In chess, comebacks in the endgame are relatively difficult, and because captured pieces cannot be reused, it is hard to recover from an early disadvantage.

Additionally, the power and range of the pieces are generally stronger than in shogi. For these reasons, chess requires extremely precise move selection from the opening, as even small mistakes are likely to be punished immediately.

In shogi, by contrast, it is often possible to recover in the endgame, since the opponent is likely to make mistakes later anyway. As a result, the importance of the opening is relatively lower. Even without finding the absolute best moves, players can survive by maintaining reasonable piece development and structure.

It is sometimes said that professional shogi players around the 1980s would even chat casually during the opening phase. In recent years, however, shogi AI has surpassed human strength and has systematically refined opening theory, making such an approach obsolete.

Still, compared to chess, shogi openings tend to be more forgiving. Because the opening is less decisive, shogi offers a wider variety of viable opening systems. Even at the professional level, players can often manage without memorizing exact opening lines, which is another major difference between the two games.

Conclusion

• Garry Kasparov pointed out that the reuse of captured pieces is a key difference between shogi and chess.

• This difference manifests most clearly in both the opening and the endgame.

• In shogi, piece reuse allows the wide range of possible moves seen in the opening to persist into the endgame.

• Because shogi endgames are highly complex, the opening tends to be relatively forgiving, resulting in a greater variety of viable strategies.

Q1. Is shogi more complex than chess?
In terms of branching factor, yes. In terms of difficulty, no. In shogi, the branching factor remains high due to the possibility of dropping captured pieces. This means shogi maintains a high number of possible moves throughout the game.
However, in terms of actual difficulty, it does not necessarily matter, because chess requires deeper calculation.

Q2. Why are shogi endgames so difficult?
Because captured pieces can be reused, the number of possible moves does not decrease in the endgame, unlike in chess. As a result, there are many possibilities to consider even in the endgame, making it very challenging.
Even professional players often experience reversals or make mistakes.

Q3. Did Garry Kasparov really play shogi?
Kasparov has played shogi during visits to Japan. He also commented on the unique feature of piece reuse in shogi. However, he never pursued the game competitively.