ChessBase

For the Slav and Semi-Slav Powerbook 2021 the ratings average was set at 2400. 1.76 million games from the engine room of playchess.com met this threshold, to which were added over 80 000 games played by humans.

Slav and Semi-Slav Powerbase 2021 is a database and contains a total of 10 610 games from Mega 2021 or the Correspondence Database 2020, of which 1030 are annotated.

The major part of the material on which the Caro-Kann Powerbook 2021 is based is taken from the engine room of playchess.com: 736 000 games. To that imposing corpus we have added another 58 000 games from Mega and from correspondence chess.

Caro-Kann Powerbase 2021 is a database and contains a total of 9549 games from Mega 2021 or the Correspondence Database 2020, of which 745 are annotated.

Almost 1 million games from the engine room of playchess.com form the basis of the English Powerbook 2021, with in addition 105 000 games from Mega and from correspondence chess.

English Opening Powerbase 2021 is a database containing in all 10 337 games from Mega 2021 or Correspondence Database 2020, of which 645 are annotated.

Top class material was used for the King’s Indian Powerbook 2021: over 100 000games from the Mega and from correspondence chess, and in addition more than 264 000 games from the engine room of playchess.com, in all 372 000 games.

King’s Indian Powerbase 2021 is a database and contains a total of 11092 games from Mega 2021 or the Correspondence Database 2020, of which 839 are annotated.

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.