X's and O's is the culmination of several years of unexpected obsession with the game of tic-tac-toe.

It all began at a Christmas tree farm where they had tables covered with tic-tac-toe boards. As I was teaching my then 3-year-old son how to play, I started to wonder: how many different games of tic-tac-toe are there really? It seemed like we were just playing the same game over and over.

So I went home and wrote some code to try to calculate it, making some assumptions about how reasonable people would play, and factoring out games that were simply rotations or reflections of other games. I then made a YouTube video about it, which immediately exploded, receiving millions of views in the first couple of days.

I try not to be a slave to the algorithm, but between the wild popularity of the video and my increasing obsession with the topic, I made quite a few videos about tic-tac-toe in the coming months.

Fast-forward a year or two, and I found myself having a conversation about tic-tac-toe with composer and musical geometer Dimitri Tymoczko. He pointed out that the rotational and reflectional symmetries of the tic-tac-toe board had a natural analog in the transpositional and inversional symmetries of pitch classes, and proposed the following mapping of board squares to pitch classes:

F	G	A♭
E	C E♭ F♯ A	B♭
D	C♯	B

By mapping the pitches in this way, each quarter-turn of the board corresponds to transposition by a minor 3rd, so tic-tac-toe games that are rotations of one another yield melodies that are transpositions of one another. Similarly, reflecting a tic-tac-toe game along the x- or y-axis results in the melody being inverted (though within the octatonic scale rather than chromatically).

One other interesting quirk you might notice is that the center square has four pitch classes instead of one, forming a C diminished 7th chord. This is because the center square is the one square that does not change position when the board is rotated, so its pitches have to stay the same under transposition. In the piece, I took two approaches with this square: sometimes it was mapped to the whole diminished 7th chord; other times it was simply mapped to the pitch of the chord nearest to the previous pitch played.

Tell you what, the best way to understand it is probably just by playing with it:

Anyway, this struck me as a rich potential space for an audiovisual composition, one which tells the universal story of playing tic-tac-toe until every game ends in a draw.

I finally got the chance to do this at the 2026 SPLICE Institute, working closely with cellist Joy Chu on a duet for cello and electronics.

I conceived of the piece in three sections: first, the cellist finds herself transported to tic-tac-toe-land, a place where every note she plays causes a circle to appear on the board. She explores for a while, discovers the magic of getting three in a row, and then, just when she's starting to feel confident, the electronics enter with an X, throwing a wrench into the works. Musically, I used this opening section as an opportunity to freely explore the melodic and harmonic possibilities of the musical mapping.

The middle section then takes the form of a duel between the cellist and the electronics: a repeated series of tic-tac-toe games, at first tentative, and then increasingly frustrated. I wanted to sequence the games in a way that made sense both ludically and musically, and ultimately found myself building a little program where I could explore every possible game, filtering for certain melodic or harmonic qualities. Unlike the outer sections, this section has a pulse, with hocketed rhythms and additive meters falling naturally out of the structure of the game itself.

In the final section, once the futility of the game is recognized by both parties, they circle one another, ultimately arriving at a beautiful, if slightly cheesy, moment of reconciliation.

I owe a great debt of thanks to cellist Joy Chu, who was — no pun intended* — a total joy to work with.

You can see the full score here.

* This is a lie. The pun was indeed intended.