Quantum Tic-Tac-Toe: the best game you’ve never played, or have you?

Darren Broemmer
6 min readSep 17, 2022
Background Photo by Dan Cristian Pădureț on Unsplash

Tic-tac-toe is a boring game after the first few times, right? We learn it as a kid and later lose interest due to its simplicity. Later in life, we play it with our kids and let them win once in a while. One big problem is that any use of skill or strategy ends up in a tie game.

What if, however, you could play two moves at once? That would make it more interesting and challenging, right?

What if each of these “quantum” moves were actually potential games we were playing simultaneously? The game just became a little more interesting. There are now seemingly more winning strategies. (Actually, it’s the same but it’s harder to keep track of them.)

What if two skilled players each had a chance to actually win a game of tic-tac-toe instead of settling for a tie?

What’s quantum got to do with it?

Quantum physics is one of the most accurate and productive theories that exist in all of science. Yet, it is almost incomprehensible at first glance. And after a second glance and probably a third. Even the great physicist Richard Feynman said “I think I can safely say that nobody understands quantum mechanics.” This is a man who was once called the smartest person in the world in 1979.

Fortunately, Allan Goff created a game that helps us understand the theory. The game is a quantum version of Tic Tac Toe. I have created a website where you can play quantum tic-tac-toe if you want to check it out.

The theory of quantum physics captures the seemingly strange behavior of the atomic world. Electrons within an atom, for example, act like waves when we are not watching and particles once we observe them. That makes sense, right? Feynman was no dummy.

The foundational concept is called superposition. This refers to the condition where an element appears to take have more than one state or take more than one path simultaneously. In our game, this takes the form of “quantum moves”. On each turn, player X or O is allowed to make two quantum moves, each of which represents a possible move being played simultaneously. At this point, however, the moves are not real (what we deem to be classical). Quantum moves can’t be used to win the…

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Darren Broemmer

I write weekly on puzzles, science, and technology. Technologist, published author, ex-BigTech, indie publisher.