For this first launch of the Grünfeld Powerbook an Elo average of at least 2300 was set. Thus 70 000 games from Mega and from correspondence chess met the threshold of the Powerbook, and to them were added 232 000 games from the engine room of playchess.com. The Grünfeld Defence embodies a modern plan: Black concedes the centre to White and goes on to attack it with all his might. For years that seemed so risky that there was even a search for a refutation. But it should give at least a safe and nice advantage to White. Yet the Grünfeld Defence has proved itself viable not only in the legendary WCh matches Karpov-Kasparov. Later almost every world class player took up the opening in his or her repertoire for Black and nowadays players with White would be glad if there were at least one line in which a teeny-weeny advantage could be achieved. So from the theoretical point of view White has so far not managed much and that makes the search for venomous little side variations all the more important and rewarding. The Powerbook is outstandingly suitable for that purpose.
With the Grünfeld Defence Powerbook 2021 lovely discoveries can be made. In the position after 4.cxd5 Nxd5, for example, there are the continuations 5.Bd2 and 5.Na4.
The yield is no worse than after 5.e4, but the amount of effort to learn the theory is considerably less. Moreover, the knight move offers the advantage that Black has to do without his usual c7-c5.