Solving puzzles is part of every serious chess training. Positions to feed to students used to be the core asset of professional coaches. Mark Dvoretsky’s exercises included combinatorial sequences that were so hard that grandmasters took hours to find them, if they could find them at all. At the opposite end of the spectre, the Step Method revolutionized chess instruction by prompting beginners to one-move-tasks: Attack a piece, find a check, capture a piece, detect the piece under attack, defend the piece and so on. László Polgár collected tactics to train his three daughters. Out of these he chose 5334 positions to produce what must be the heaviest mass-printed chess book, weighing close to three kilograms (or six pounds in America).
Nowadays most players prefer to solve puzzles interactively on a screen. In the digital age we have gotten used to big numbers. Still, the 653,728 puzzles that Lichess published on Christmas Day set a new record, and meanwhile the number has even grown to 710,525 puzzles.
It is not only more than ten times bigger than the former Lichess collection. It is now also organised by themes, which makes them much more valuable, as Rafael Leitao pointed out in his review of the Tactics Frenzy app. The puzzles are ordered by motives, by game phase or type of ending, by the length of the mating or solving sequence, and by the goal (from equalizing to checkmate). The positions origin from games played on the platform. True to its open source philosophy, Lichess makes the whole database of puzzles available for download. Coaches will find this useful when they assemble exercises on a certain theme.
When it comes to high quality puzzles, gamification, and personalization, Lichess has left more than enough room for other developers.
Are commercial tactic trainers now obsolete? Not really. For usability, the puzzles need to be more selected and adjusted to the strength and goals of the solver. Lichess says that the puzzles will be rated in cooperation with Aimchess. This will be a significant step towards making them digestible.
If you choose a “healthy mix” of puzzles now, you encounter mostly trivial examples. Lichess is asking the users to rate the puzzles and has published an update on how this has been going. Once sufficient user ratings are processed, this should help, too. However, their announced goal is not to boil down the collection to non-trivial ones, but to make it even bigger. The next goal is make it a million positions. Quantity over quality.
Responding to feedback on puzzles that were ambigeous or simply didn’t work, Lichess now avoids positions that have more than one solution or require the calculation of not just one main line. The solutions sequence ends when the best move is not clear. This bias adds to the triviality of the material. Apart from high quality puzzles, gamification is another aspect Lichess leaves to other developers. Chess.com is currently promoting its Puzzle Rush with a public competition. Yet another aspect that remains is the personalization of tactics training.