ChessBase

The Ruy Lopez Powerbook 2021 has a tree structure based on 2.23 million computer chess games played in the engine room of playchess.com.

Ruy Lopez Powerbase 2021 is a database and contains a total of 10370 games from Mega 2021 and the Correspondence Database 2020, of which 1172 are annotated.

The main part of the material on which the French Powerbook 2021 is based comes from the playchess.com engine room: 637,000 games. An impressive number to which 80,000 games from correspondence chess and the Mega were added.

The French Defence Powerbase 2021 is a database and contains 9839 games from the Mega 2021 and the Correspondence Database 2020, 644 of which are annotated.

The major part of the material on which the Sicilian Dragon Powerbook 2020 is based comes from the engine room of playchess.com: 160 000 games. There have been added another 12500 games from Mega and from correspondence chess.

Sicilian Dragon Powerbase 2020 is a database and contains 4997 top class games from Mega 2021 and the Correspondence Database 2020, of which 730 are annotated.

Scandinavian Defence Powerbase 2020 is a database and contains a total of 5492 games from Mega 2020 and the Correspondence Database 2020, of which 437 are annotated.

The major part of the material on which the Scandinavian Defence Powerbook 2020 is based comes from the engine room of playchess.com: 79 000 games. To this have been added 11 000 games from Mega and from correspondence chess.

Petroff Defence Powerbase 2020 is a database which contains 4821 high class games from Mega 2020 and the Correspondence Database 2020, of which 648 annotated.

The major part of the material on which the Petroff Defence Powerbook 2020 is based comes from the engine room of playchess.com: 260 000 games. This imposing number is supplemented by another 11 000 from Mega and from correspondence chess.

The Dutch Defence Powerbook 2020 consists for the greater part of engine games (70 000), to which have been added high value material from Mega and the Correspondence Chess Database (30 000).

Dutch Defence Powerbase 2020 is a database and contains a total of 7890 games from Mega 2020 and the Correspondence Database 2020, of which 688 are annotated.

The major part of the material on which the King's Gambit Powerbook 2020 is based is sourced from the engine room of playchess.com: 30 000 games. Another 3500 games from Mega and from correspondence chess have been added to this corpus.

King's Gambit Powerbase 2020 is a database and contains a total of 2531 games from Mega 2020 or the Correspondence Database 2020, of which 112 are annotated.

The Ben-Oni Powerbook 2020 consists for the greater part of engine games (44 600), to which has been added high-value material from Mega and the Correspondence Database (23 600).