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Chess is not about perfection, it is about creativity, ideas, and consistency. You can play 50 perfect moves, and blunder checkmate in completely won position, and you will still lose the game.

Therefore we do not expect you to play top engine move, and, as opposed to other chess puzzles game, there is more than one correct answer.

We analyzed thousands of games (still counting) with 100K+ available positions, to face you with real positions that occurred in real games, on various levels. You play your move, and we analyzed every possible response, so you don’t get an answer: correct/incorrect, but evaluation how good or bad your move is. We measure that based on evaluations that chess engine is providing us with.

There comes the subject of inaccuracy: lets say that top move gives you +0.55 evaluation (which means that white is roughly half of a pawn value better). You don’t play that move, but move that evaluates your position as +0.15 now. You cannot say it is a wrong move. It is not top engine move, but it doesn’t have to be. In order to calculate how good is your move, it is not sufficient to deduct these values. Because if you loose 2 points in +10 positions, it is still pretty much the same (you are still winning), but if you go from +1 to -1 it has more drastic effect on expected outcome. So we don’t consider pawn evaluation, but WP (win percentage) expectation.

With +0.55 evaluation, chances for white are 57.85%, based on huge number of played games on top level. Meaning that there draw is most expected outcome, but white has a bit better chances (compared to 42.15% that is left for black).

With +0.15 evaluation chances for draw is increased, and white has 52.16% expected outcome.
Therefore, it is treated as 57.85-52.16 = 7.69

And that is your inaccuracy for that move. So, in time, you will learn that it is not important to play top move, it is important to be consistent, and not got from +5 to -5, and loosing almost all 100%. It will impact your inaccuracy largely, same as it happens in your real game

There are some trivial positions, what's the point?

Yes, you are correct. We had a large debate over it. Why would we live positions that has -10 evaluation, and even if you play top move, you are still lost, and if you play worst move, it is actually inaccuracy that has like 0,1 value in percentage, maximum? Or, even more drastic, you can face a position with only one legal move, so you can’t even theoretically be mistaken?


Well, conclusion is that we don’t wanna compromise REALITY part of our game. So, in reality you are facing such moves, and we will keep it that way. Also, it would affect your overall inaccuracy if we would skip these easy gains for you.

Only mover that we leave out from real games are the moves from very beginning, don’t want to judge you if you start with E4, D4, or even A3 (although for the last one we maybe should!)

Okay, inaccuracy is clear, how does it translate to my ELO

We are aware that inaccuracy is a measure that requires a lot of explanation in order to be understandable. And, in order to give our players a known reference system, we translated it into ELO. Again, long hours of compute power was used to produce estimate on how well different players with different ELOs perform, and to calculate their inaccuracy retroactively.

Data matrix was produced, and we managed to map these two values, therefore you can have a better understanding what can you expect in real games. If you play 500 games, let’s say it is average number of moves you will play in a tournament, and ELO you have will resemble your performance rating as close as possible.

Please have in mind that we refer to FIDE rating. Many online chess platforms will give you unrealistic ELOs (like on largest platforms many players are over 3000, and current world champion Magnus Carlsen is having a life-time goal to reach 2900, and he is failing so far). So, do not despair if your ELO here is lower than on some other online chess platform, it is expected behavior.

Our goal is to HAVE YOUR REALITY CHECKED!
Goal is to work on your real chess skills, and only valid measure is FIDE rating, therefore we focus on give our estimate on that.

Chess is not about perfection, it is about creativity, ideas, and consistency. You can play 50 perfect moves, and blunder checkmate in completely won position, and you will still lose the game.

Therefore we do not expect you to play top engine move, and, as opposed to other chess puzzles game, there is more than one correct answer.

We analyzed thousands of games (still counting) with 100K+ available positions, to face you with real positions that occurred in real games, on various levels. You play your move, and we analyzed every possible response, so you don’t get an answer: correct/incorrect, but evaluation how good or bad your move is. We measure that based on evaluations that chess engine is providing us with.

There comes the subject of inaccuracy: lets say that top move gives you +0.55 evaluation (which means that white is roughly half of a pawn value better). You don’t play that move, but move that evaluates your position as +0.15 now. You cannot say it is a wrong move. It is not top engine move, but it doesn’t have to be. In order to calculate how good is your move, it is not sufficient to deduct these values. Because if you loose 2 points in +10 positions, it is still pretty much the same (you are still winning), but if you go from +1 to -1 it has more drastic effect on expected outcome. So we don’t consider pawn evaluation, but WP (win percentage) expectation.

With +0.55 evaluation, chances for white are 57.85%, based on huge number of played games on top level. Meaning that there draw is most expected outcome, but white has a bit better chances (compared to 42.15% that is left for black).

With +0.15 evaluation chances for draw is increased, and white has 52.16% expected outcome.
Therefore, it is treated as 57.85-52.16 = 7.69

And that is your inaccuracy for that move. So, in time, you will learn that it is not important to play top move, it is important to be consistent, and not got from +5 to -5, and loosing almost all 100%. It will impact your inaccuracy largely, same as it happens in your real game

There are some trivial positions, what's the point?

Yes, you are correct. We had a large debate over it. Why would we live positions that has -10 evaluation, and even if you play top move, you are still lost, and if you play worst move, it is actually inaccuracy that has like 0,1 value in percentage, maximum? Or, even more drastic, you can face a position with only one legal move, so you can’t even theoretically be mistaken?

Well, conclusion is that we don’t wanna compromise REALITY part of our game. So, in reality you are facing such moves, and we will keep it that way. Also, it would affect your overall inaccuracy if we would skip these easy gains for you.

Only mover that we leave out from real games are the moves from very beginning, don’t want to judge you if you start with E4, D4, or even A3 (although for the last one we maybe should!)

Okay, inaccuracy is clear, how does it translate to my ELO

We are aware that inaccuracy is a measure that requires a lot of explanation in order to be understandable. And, in order to give our players a known reference system, we translated it into ELO. Again, long hours of compute power was used to produce estimate on how well different players with different ELOs perform, and to calculate their inaccuracy retroactively.

Data matrix was produced, and we managed to map these two values, therefore you can have a better understanding what can you expect in real games. If you play 500 games, let’s say it is average number of moves you will play in a tournament, and ELO you have will resemble your performance rating as close as possible.

Please have in mind that we refer to FIDE rating. Many online chess platforms will give you unrealistic ELOs (like on largest platforms many players are over 3000, and current world champion Magnus Carlsen is having a life-time goal to reach 2900, and he is failing so far). So, do not despair if your ELO here is lower than on some other online chess platform, it is expected behavior.

Our goal is to HAVE YOUR REALITY CHECKED!
Goal is to work on your real chess skills, and only valid measure is FIDE rating, therefore we focus on give our estimate on that.

About Author

Hey there, fellow chess enthusiasts!

Welcome to my corner of the “RealityCheck Chess“.

I’m Marko Milošević, a mathematician, software architect, and an unapologetic lover of all things chess. Born in 1985 and proudly hailing from Serbia, I’ve embarked on a thrilling journey that combines my two greatest passions: programming and the timeless game of chess.

In the world of chess, I found both comfort and excitement. Its complexity and depth drew me in, inspiring me to improve and to create something for fellow chess lovers. “RealityCheck” is the result—a blend of my commitment to chess, math skills, and software development designed to enhance your chess skills.

I bring my mathematical background to chess, analyzing games and strategies with precision. By day, I’m a software architect; by night, a chess aficionado, delving into tactics and grandmaster plays. I’m also active in chess communities, participating in tournaments and learning from others.

I’m eager to share “RealityCheck” with you and discuss all things chess. Contact me at marko@monstersnations.com for questions or a good chess conversation.

Remember, “RealityCheck” is not just a chess game—it’s a catalyst for growth, a tool for self-improvement, and a virtual playground where chess lovers like us can thrive.

Thank you for joining me on this exciting adventure. Together, let’s uncover the limitless possibilities of the chessboard!

Warm regards,

Marko Milošević

About Author

Hey there, fellow chess enthusiasts!

Welcome to my corner of the “RealityCheck Chess“.

I’m Marko Milošević, a mathematician, software architect, and an unapologetic lover of all things chess. Born in 1985 and proudly hailing from Serbia, I’ve embarked on a thrilling journey that combines my two greatest passions: programming and the timeless game of chess.

In the world of chess, I found both comfort and excitement. Its complexity and depth drew me in, inspiring me to improve and to create something for fellow chess lovers. “RealityCheck” is the result—a blend of my commitment to chess, math skills, and software development designed to enhance your chess skills.

I bring my mathematical background to chess, analyzing games and strategies with precision. By day, I’m a software architect; by night, a chess aficionado, delving into tactics and grandmaster plays. I’m also active in chess communities, participating in tournaments and learning from others.

I’m eager to share “RealityCheck” with you and discuss all things chess. Contact me at marko@monstersnations.com for questions or a good chess conversation.

Remember, “RealityCheck” is not just a chess game—it’s a catalyst for growth, a tool for self-improvement, and a virtual playground where chess lovers like us can thrive.

Thank you for joining me on this exciting adventure. Together, let’s uncover the limitless possibilities of the chessboard!

Warm regards,

Marko Milosevic

Our Testimonials

"Brilliant puzzles, helped me in learning chess!!"

Rohan May 24, 2023

"Extraordinary and great quality app. Never gets boring!"

Marko Vukosavljević October 11, 2022

"Game is pretty well done, all recommendations."

Lazar Ćosić October 2, 2022

"It's a nice app. The Masters game is really helpful."

Anirudh May 25, 2023

"Having a ball, pitting my witts against G.M. played positions, can't wait to share with my F.B. group of 130,000 members!!"

Howard Anderson June 13, 2022

"Thank you so much for this."

Adam Ouled June 6, 2023

"It's good, I love it!"

Jeren Edicto March 26, 2023