The Importance of Opening Theory

Professional chess players find it absolutely essential to keep up with current opening theory. It's even more important for chess book authors, producers of chess training videos and YouTubers, because that's how the earn their income.

How important is opening theory for club players then? To answer that, we must investigate what opening theory really is.

There's nothing scientific about it, so the word "theory" is misleading. It's really just a road map covering a huge number of well-trodden paths through the opening phase of the game. These paths are then organised into groups, usually defined the the first couple moves, and then named after the person who introduced it or the location where the opening was first played. The French Defence (1.e4 e6), the Ruy Lopez Opening (1.e4 e5 2.Nf3 Nc5 3.Bb5)  and the Grünfeld Defence (1.d4 Nf6 2.c4 g6 3.Nc5 d5) are just a few examples. The moves in bold are the characteristic moves that defines the opening.

From there it branches out in variations, sub variations and sidelines. Some have names of there own (like the Najdorf Sicilian and the Ruy Lopez, Marshall Attack). Some popular variations cover 20 moves or more, reaching well into the middle game. 

The amount of information covered by opening theory is absolutely overwhelming. To narrow it down most players focus on just a few lines as White and as Black, and memorise those. This works well for Grandmasters, but for club players, is a complete waste of time. Here's why:

A Grandmaster knows what's in fashion at the moment, and what their opponents usually play. When faced with an unexpected move, a GM has a deep understanding of the position at hand, and can now start working out the continuation.

At the club level, anything can happen at any time, and it usually does - around move three or so. At that point, your memorised lines are useless. Since club players are notoriously bad at assessing unfamiliar positions, the game can now take off an any direction, most of them bad.

In this example, my opponent was a booked-up teenager with the White pieces:

1.e4 c6 2.d4 d5 3.ex4 cxd4 4.Nc3 Nf6 5.Bf4

White is threatening Nc3-b5-c7 winning the rook. This can be parried in several ways, but I decided on:

5...a6 

This avoids any unpleasantries on b5, and also prepares for a future pawn push to b5. The position is about equal, without immediate threats, and both players can now proceed with the development of their pieces.

After the game, my opponent told me he was completely taken aback by that move, and said disappointedly "that's not how they play the Caro-Kann". He never recovered from the shock, and proceeded to make several mistakes, arriving at a completely lost position by move 13. 

Back home, I learned that 4.Nc3 is frowned upon by theory, c4 or Bd3 are the popular choices. Also, 5...a6 is actually the main line here, so my opponent had probably mixed up the variations. I knew nothing about any of that at the time of the game, but those fine nuances are not important at this level.

Takeaway

Get rid of that habit of memorising opening lines. They will not do you any good. Instead, focus on understanding the positions that arise from your openings, and the ideas behind them.

How to find the Mistakes

 When you get home from a tournament game, the first thing you do is to scrutinise the game in search for your mistakes. For each mistake, you ask yourselves two questions:

1. Why did I play that?
2. What should I have played instead?

The first question is hard, so we usually dismiss it. The second one is easy though, just start up your chess engine, and it will immediately tell you just how bad your move was, and what you should have played instead.

What do you gain from that exercise? Nothing of any value. You are debunked as weaker than Stockfish. You already knew that, but it still makes you feel bad. Secondly, it doesn't help to memorise the move Stockfish suggests. You'll probably never get into that position again, and if you do, the move to play is long forgotten.

Instead, focus on the first question. You'll find that the answer often lies not in the move as such, but the events leading up to it. What was going on in your mind when you played that move, earlier in the game, before the game, and the day before yesterday? This may sound confusing, so I'll use a game to clarify the concept.

This was a postponed game, so there were only ten players ar the venue. I arrived ten minutes early, which is too short for my preferences, but I still looked forward to having ten minutes to get in the mood. However, the referee greeted me with "The other players are all here, so you may start your game immediately". I could, or rather, should) have insisted on my ten minutes, but I sat down, shook hands, and made my first move.

Me - N.N. (Open Tournament, 2025)
English Opening

1. c4 e5 2. Nc3 Nc6 3. g3 Bc5 4. Bg2 d6 5. e3 Nge7 

 

 Up to this point, it was all on auto pilot, but the last move disturbed me. Now I had to start thinking, but as I mentioned earlier, I wasn't quite ready for that. After pondering a good while over 6. Nge2, I decided to grab some space on the queenside as I usually do in this kind of position.

6. a3 Bf5 Aggressive, but a6 or a5 was better.
7. b4 Bxb4 Did my opponent find something devastating at the board, or was it home preparation? I quickly rejected the latter alternative, because that's not something club players do. It wasn't a spark of divine inspiration either - after the game, he told me that he thought that the Bishop was trapped, and that the capture was the only way out. 

8. axb4 Nxb4 9. Qa4+

Desperately wanting to chase away the Knight. 9.e4 would have been better, even if Black stops any castling plans by Nd3+. Still, White is clearly better after Qa4+, but I had no idea how to proceed.

9... Nec6 10. e4 Realising that this should have been played a move before, I figured that I should work here too, but it was too late. The best alternative was 10.Bxc6 Nxc6 11.d4, avoiding all of the troubles ahead. But, I had already decided to keep the Bishop to provide a safe home for my King.

10... Bd7 As we saw in my previous post, a mistake is often answered with another mistake. This hands the advantage back to White. 10...Nd3+ was still the move to play.

11. Kd1 This is probably a decisive mistake. I was worried about the fork on c2 after Nd4, but that could have been taken care of with 11,Qd1.

11... Nd3 So far, this has been a game between two players with their minds elsewhere, playing well below their normal standards. Now, however, Black wakes up and starts to play chess.

12. Ke2 Unfortunately, it's now too late for White to level up, this move puts an end to all survival chances. The f2 pawn needed protection, but Black has another Knight to throw in.

12... Nd4+ 13. Kxd3 Bxa4 14. Rxa4

  

White has three pieces for the Queen, but the position is totally lost. Black finished it off like this:

O-O 15. Bb2 c6 16. Nh3 b5 17. cxb5 cxb5 18. Ra6 Qc8 19. Rha1 Qc4+ 20. Ke3 b4 21. d3 Qb3 22. Rb1 bxc3 23. Bxc3 Qxb1 24. Bxd4 exd4+ 25. Kxd4 Qb4+ 0-1

Takeaway

After a game like this (and we all have them from time to time), it's pointless to do any "What should I have played instead" exercises. The big mistake here (by both players, but more so by White), was not being mentally and physically prepared for the game. You must do that before the game, when the clock starts, you can only work with what you have.

 

Always Expect the Unexpected

Have you noticed that a bad move will frequently be answered with another bad move, foregoing the chance to take advantage of the mistake? Is that due to a gentlemanly gesture, or are there other mechanisms at work?

As for me, there's no gallantry involved when this happens. Just as most of my peers, I handle surprises poorly. We fail to accept that an unexpected move wrecks our plan, and we must now make a new one (on the bright side, if the unexpected move is bad, your new plan will yield better than the old). Instead, we just carry on as if nothing happened, which most often leads to disaster. This game has several examples of mishandling surprises, both by me and my opponent.

 Me - N.N. (Swedish League, 2025)
English Opening

1. c4 Nf6 2. Nc3 e5 3. g3 Bc5 4. Bg2 Nc6 5. e3 O-O 6. Nge2 a6 7. O-O d6 

 

 So far, both players have made sensible moves. White now has a number of good moves: d3, d4, a3, b3 or h3 are the popular choices.

8. Nd5 Not really a mistake, but premature, as it can be punished right away with Nxd5.
Bg4 Black sticks to the plan. 
9. Nxf6+ A waste of time. h3 or b3 were still good options 
Qxf6 10. Kh1  

In just a few moves, White's position has gone from better to worse. White is behind in development, and the Knight is pinned.

10... Rab8 11. f3 Be6 12. Qc2 The first mistake. Why not play b3? When a move is rejected (in this case 8.b3 and 9.b3), it somehow disappears from the radar. Now Black can gain a strong initiative by 10...b5 11.cxb5 Nb4, but gives that away by 
Nb4 13. Qc3 (this would not work with the c-pawn gone) 
Rfd8 The first real blunder. b5 was still the move to play. 
14. d4 Finally! White has been aching to play this for a long time. 
b5 The best move, but now it's too late. 

White has a winning position - the Bishop is hanging. Instead of the capture, 15.d4 would be even better. I pondered that for a long time (too long, as it turned out), but wasn't able to calculate the consequences. So, I took the safe route, which is nearly as good. 

15. dxc5 dxc5 16. f4 Wins the award for "Worst blunder of the game". I had the perfectly good 16.b3 bxc4 17.f4 in the back of my mind, but for the fourth and last time in this game, b3 slipped away. 
Bxc4 17. fxe5

Now Black could secure the win with 17...Qb6. That's not an easy move to find, and neither of us had any thoughts in that direction during the game. It follows 18.Bf3 Rd3 19.Qe1 Nc2 and the Rook falls.

 Qe7 This is second best, but allows White to restore equality with 18.Nf4 Bxf1 19.Bf1. However, there's still time to blunder!
18. a3 18... Rd3 Black could have finished it off with 18... Bxe2, but fatigue and time pressure is taking its toll on both players.
19. Qxc4 bxc4 20. axb4 cxb4 21. Nd4 Rb6

White has three pieces for the Queen and two pawns, There are survival chances after 22.Bd5, but with no strength left, I found a much weaker move.

22. Be4 Qxe5 A winning move. The rest of the game contains some more mistakes, but the win was never at risk from this point.
23. Bxd3 cxd3 24. Rf5 Qe4+ 25. Kg1 g6 26. Rfa5 Qb7 27. Nb3 Rf6 28. Nc5 Qf3 29. Bd2 Qf2+ 30. Kh1 Qxd2 31. Ne4 Qxb2 32. Nxf6+ Qxf6 33. Rxa6 Qf3+ 34. Kg1 Qxe3+ 35. Kf1 Qe2+ 36. Kg1 d2 37. Ra8+ Kg7 38. Rd8 Qe1+ 0-1 

Takeaway

The mistakes we make in response to a mistake by the opponent can be avoided by accepting that the position after an unexpected move is new to you. It didn't appear in any of your plans, so you'll just have to scrap them and start over.

Finding Candidate Moves

I sometimes train new players at my chess club, and that gives me valuable insights into obstacles new players experience starting out their chess career. By the way, these new players are not beginners, but typically someone who has played online chess for a while, and wants to try club chess.

All of them have problems with setting up the board, handling the clock, and writing down the moves - their online chess service has always done that for them. However, the biggest problem is finding the move to play. When asked how the pick their moves, they say things like "I want to attack the King, so I look for moves that support that idea" or "I fear that he's attacking my King, so I look for moves that prevent that".

That's when I say "It's not you who decide what to move. The right move is hidden in the position, and your job is to find it." That's typically met with a blank stare. So what does it mean? Is there no room for free will in chess?

In chess books, you'll frequently see the expression "the position demands...". That means that the position wants to develop in a certain way, or more often, in one of several ways. 

To find those moves. you need to develop your positional intuition. You do that by solving a lot of positional puzzles. These are not easily found online, but Lichess has a study on the subject. Combine this with analysing your own games. Find a critical position (i.e. where you didn't know what to play), and now, with Stockfish off, try to find some moves. That's much easier at home than during the game! When you're satisfied with your candidate moves, switch on Stockfish to have them evaluated. Don't worry if they are brutally dismissed. If Stockfish suggests something you didn't consider, take a moment to figure out why that move is good, and your moves were bad. Then move on to the next game and do it again.

 

Why Calculation is Bad for You

We often use pairs of opposites when we talk about personality traits - kind or mean, generous or greedy. In What's Your Style in Chess?, we looked at some opposite pairs used to describe different styles in chess. This time, we'll dive into Calculation.

Calculating players tend to distrust or not paying attention to their intuition. They feel the need to calculate each and every line as deep as they possibly can, and as a consequence regularly end up in time trouble or fatigue. The main cause for time trouble is that they spend too much time on irrelevant lines. Lets do the maths: A standard position offers three plausible candidate moves on average. If each of those has three replies, we have nine different lines to calculate. After your next move, you have 27 positions to evaluate, but only one of them can actually happen in the game. So, if you spend one minute on each position, you have wasted 26 minutes on lines that didn't happen. How many times can you afford that in a single game?

All that calculation can also cause whatever intuition you have to wither and die, and that leaves you with calculation as the only tool in the box.

Intuitive players, on the other hand, tend to pick the candidate move that feels best, and just play it without further ado. Very soon they're half an hour ahead of their calculating opponent. However, this doesn't mean that intuitive players have an advantage. Intuition may provide quick answers to complicated questions, but they're not always right. Calculating players make fewer and less serious mistakes, so if they only succeed in managing their time, they can level the field.

In order to improve, both types of players must venture out of their comfort zone. Intuitive players must work on their calculation skills, and calculating players must learn how to trust and listen to their intuition.

Takeaway

We are what we are, but it's not a good idea to only play on your strengths. Every game requires both intuition and calculation, and to be a better player, you need to work on your weaknesses too. Intuitive players can work on their calculation abilities during their games, but it's harder the other way around. A good training practice for calculating players is to solve puzzles without calculating. Just stare at the position until a move presents itself. If it's the right move, move on to the next puzzle, and if it's not, take some time to figure out what went wrong.

 

The Perfect Play Syndrome

Last time, we saw that chess will not be solved by brute force methods anytime soon (if ever). Can Perfect Play provide a solution? 

Wikipedia says: In game theory, perfect play is the behaviour or strategy of a player that leads to the best possible outcome for that player regardless of the response by the opponent. Perfect play for a game is known when the game is solved.

That last sentence means that perfect play is unknown for unsolved games like chess, so trying to solve chess by perfect play is not possible. Still, that doesn't prevent some players, obsessed with the idea of perfect play, from spending oceans of time trying to solve at least the position they have in front of them. That's futile, because almost all positions are insolvable. We can solve mate puzzles, and endings with seven pieces or less, but that's about it.

Even ancient seafarers used navigational charts to arrive safely at their destination. In chess, we have opening manuals serving the same purpose. While navigation now can be considered solved, nearly all possible chess positions remain in uncharted territory as we saw in the previous article.

Before navigation was solved, some daring seafarers like Leif Eriksson or Christofer Columbus ventured off the map, even a the risk of perishing in unknown waters, and found America. Many others, unmentioned in the history books, went under trying.

It's tempting to view the main line in the manual as perfect play, but it's really just a well tested line with a good performance score. Any early deviation can lead to previously unknown positions, and some of them can actually be better than the main line (although most of the are rubbish).

Sometimes we see a TN mark after a move. A Theoretical Novelty is a move from a standard book position that is previously unknown to (or discarded by) established theory, a Columbus Move if you like. If the new move proves successful, it will replace the old move as the main line, if not, it will perish at sea.

Takeaway

Trying to achieve perfect play can be rewarding in many ways, but it will not help you to win your games.

Can Chess be Solved?

I use to follow the Quora chess space to catch up on what people ask about chess. Questions about solving chess are frequent, but not as frequent as "What's the best opening?". The most popular answer, and probably the most correct one (to both those questions) is "We don't know". It's a logical question though - chess is a complete information game, meaning that the pieces, the squares and the rules of chess are fully available to both players att all times. In theory, all complete information games can be solved (Tic-tac-toe is easy to solve).

A game of chess can be described as a path of linked positions, where each move leads to a new position. The game continues until a decisive position (check mate or draw) is reached. Now, if we can chart all possible paths (like in the tic-tac-toe example), we would have solved the game. The problem with this approach is that there are 10^120 (a one followed by 120 zeros) possible legal positions in chess (that's a guess known as the Shannon number). 

As a comparison, the known universe consists of 10^80 atoms (also a guess, the Eddington number). If we could build a computer that use every atom in the universe to store chess positions and their relations (ignoring limitations such as the speed of light), we would need to store 10^40 positions in each atom.

This doesn't stop people from trying. The Chinese Chess Cloud Database now (at the time of writing) has  48 782 458 363 positions. That's an 11-digit number, to be compared with Shannon's 121 digits.

This leads us the the conclusion that chess won't be solved by brute force anytime soon. 

Another try is the Perfect Play strategy. The idea behind this is that in every position, there is one (or a few) perfect move that leads to the best possible outcome for that player regardless of the response by the opponent. In the starting position, the Chess Cloud Database offers four candidates for perfect play: d4, e4, Nf3 and c4. That reduces the number of possible positions after White's first move from 20 to 4, and after Black's first from 400 to 16. That might sound promising, but even using a Perfect Play strategy, the number of possible positions will be be far beyond what's solvable.

There is another problem with Perfect Play - we cannot know what "perfect" is. Perfect Play is only useful in solved games, so it can't be used to solve chess. The four candidate opening moves have all scored well, but that doesn't prove that any of them is a perfect move. The worst opening move according to CCDB is g4. It has a poor performance score, and also breaks a number of established opening principles. Still, g4 might be the Perfect Move, even if it's highly unlikely. We just don't know.

The Perfect Play strategy is what modern chess engines like Stockfish use. By pruning away all branches that don't look perfect, Stockfish can calculate 30-40 moves in less than an hour on a standard PC. This almost always produce good moves, but very rarely a fantastic move (they are always in the pruned branches).

The most promising attempt to solve chess is the retrograde analysis. That means starting from an end position (check mate or draw), and working backwards. So far, this work has progressed to solving any seven-piece ending. However, Shannon will prevent a solution with this approach too. The most effcient way (to date) to store retrograde analysis is the Syzygy tablebase. Here's the current state of affairs:

An eight-piece tablebase is in the works, but it would require 2 PB of disk space. That's a lot. To solve chess, a 32-piece tablebase would be required, and Shannon says no long before that. 

Takeaway

It looks like chess will remain unsolved, and continue to be a struggle between mere mortals with all our flaws and shortcomings. The outcome of the game will still be decided by mistakes. That's good!