ChessBase

The Najdorf Powerbook 2020 has a tree structure which is based on 3.69 million computer chess games played in the engine room of playchess.com.

The Sicilian Najdorf Powerbase 2020 is a database and contains 10119 games from the Mega 2020 and the Correspondence Database 2020, 1010 of which are annotated.

The greater part of the material on which the Rossolimo/Moscow Powerbook 2020 is based comes from the engine room of playchess.com: 226.000 games. This imposing amount is supplemented by some 25 000 games from Mega and from Correspondence Chess.

The Rossolimo-Moscow Powerbase 2020 is a database and contains a total of 8111 games from Mega 2020 or the Correspondence Database 2020, of which 575 are annotated.

The major part of the material on which the Grünfeld Defence Powerbook 2019 is based comes from the engine room of playchess.com: 219 000 games. To this imposing mass we have added another 60 000 games from Mega and from correspondence chess.

Gruenfeld Defence Powerbase 2019 is a database and contains 9358 top-class games from Mega 2020 and the Correspondence Database 2020, of which 1090 are annotated.

The Pirc Defence Powerbook 2019 (including the Modern Defence) consists for a greater part of engine games (160 000), to which has been added high value material from Mega and the Correspondence Database (46 000).

Pirc Defence Powerbase 2019 is a database and contains a total of 8423 games from Mega 2019 or the Correspondence Database 2018; of these 709 are annotated.

The Queen's Indian Powerbook 2019 has a tree structure which is based on a mixture of over 350 000 complete chess games played in the Engine room of playchess.com and the best games played by humans (50 000).

Queen's Indian Powerbase 2019 is a database and contains 9048 high level games from Mega 2019 and the Correspondence Database 2018, of which 593 are annotated.

The major part of the material on which the Sicilian Kalashnikov Powerbook 2019 is based comes from the engine room of playchess.com: approximately 18 000 games. To these have been added another 4500 games from the Mega database and from correspondence ch

Sicilian Kalashnikov Powerbase 2019 is a database which contains a total of 2724 games from Mega 2019 or the Correspondence Database 2018, of which 157 are annotated.

Sicilian Sveshnikov Powerbase 2019 is a database and contains a total of 8023 games from Mega 2019 or the Correspondence Database 2018, of which 548 are annotated.

The Colle-Zukertort Powerbook 2019 contains mainly engine games (53.500) and high-level material from the Mega and the Correspondence Database (4.500).

The Colle-Zukertort Powerbase 2019 is a database and contains 4703 games from the Mega 2019 and the Correspondence Database 2018, 75 of which are annotated.