For this first edition of the Petroff Defence Powerbook an Elo average of at least 2400 was the threshold. Thus 11 000 games from Mega and from correspondence chess crossed the entry threshold for the Powerbook, to which were added 260 000 games from the engine room of playchess.com. The Petroff Defence has a reputation of being a rock-solid drawing weapon, which is absolutely justified since purely theoretically White is unable to demonstrate an advantage. However, it is astonishing how often modern proponents of this opening such as Yu Yangyi, Anish Giri or Fabiano Caruana obtain on their boards exciting games full of possibilities which not infrequently end in a win for Black. So, many players with White are searching for promising side variations; this is true both of professionals and amateurs.
System requirements: Pentium PC, 2 GB RAM, Windows 10, 8 or 7 and Fritz 13, 14, 15, 16 or ChessBase 15, 14, 13 or 12 and DVD drive.
Nice discoveries can also be made with the Petroff Defence Powerbook 2020. This is true for both sides in the main variation 3.Nxe5 d6 4.Nf3 Nxe4 5.d4 d5 6.Bd3. But White more likely finds promising deviations from the mainstream after 3.d4. a) After 3...Nxe4 4.Bd3 d5 the move 5.dxe5 is the first alternative worth noting. Basically, it is still not quite clear what is the best way for Black to react – 5...Nc5, 5...Be7 or 5...Nc6. In any case here we have got away from the typical symmetrical Petroff positions. Or should one simply play the main move 5.Nxe5, but after 5...Nd7 continue with 6.Nc3!?. In any case Black completely equalises if he knows what he is doing: 6...Nxe5 7.dxe5 Bb4 8.0-0 Nxc3 9.bxc3 Bxc3 10.Rb1 0-0 11.Bxh7+ Kxh7 12.Qd3+ Kg8 13.Qxc3
and the various majorities still offer plenty of opportunities for interesting struggles. b) Or does one prefer the main move 6.Nxd7, which is frequently followed by the following sequence of moves: 6...Bxd7 7.0-0 Bd6 8.c4 c6 9.cxd5 cxd5 10.Nc3 Nxc3 11.bxc3 0-0 12.Qh5 g6 13.Qxd5 Qc7
The theory concerning this position has hardly developed at all in the last 10 years. Perhaps the branch based on over 14 000 games in the Powerbook will produce promising routes.