Tic tac toe in its earliest known form was invented around 100 BC in ancient Rome. The modern version with Xs and Os as we know it today took shape in England in the early 19th century, and the name "tic tac toe" became common in America by the early 20th century.

Here's the full timeline.

~100 BC: Ancient Rome

The story starts with a Roman game called Terni Lapilli, Latin for "three pebbles." Archaeologists have found the distinctive 3×3 grid scratched into stone surfaces all over the Roman Empire. On pavements. On walls. On the steps of the Colosseum itself.

The Roman version was slightly different from what we play today. Each player had only three pieces and had to slide them around the board rather than placing new ones. But the objective was identical: get three in a row.

Nobody knows exactly who invented it or when, but the earliest physical evidence dates to around 100 BC, making the game well over 2,000 years old.

You can play Terni Lapilli free in your browser if you want to try the original Roman version.

Early 19th century: England

The version we play today (placing a new X or O on each turn until someone wins or the board fills up) appears to have developed in England in the early 1800s.

The British called it noughts and crosses, which describes exactly what you do: place noughts (the O) and crosses (the X) on a grid. The first known printed reference to "noughts and crosses" appears around 1864, but the game was already well established as a children's pastime by then.

Late 19th century: America

The name "tic tac toe" arrived in America in the late 19th century, though it originally referred to a completely different game: a children's toy where you threw a pencil at a slate and scored points based on where it landed.

Somewhere around the turn of the 20th century the name migrated to the grid game. By the early 1900s "tic tac toe" had firmly stuck in American English while Britain kept "noughts and crosses." Same game, different names, much like football and soccer.

1952: The first computer game

Here is the part most people don't know. In 1952 a Cambridge University PhD student named Alexander Douglas built a computer version of the game called OXO as part of his thesis on human-computer interaction.

OXO ran on the EDSAC computer and displayed the game on a cathode ray tube screen. It played a perfect game and could never lose. And it predates Pong by twenty years, making it one of the strongest candidates for the title of the first video game ever made.

Today

Tic tac toe is now one of the most widely played games in the world, available on every device imaginable. Mathematicians classify it as a solved game: with perfect play from both sides it always ends in a draw. That's why it stops being interesting to adults pretty quickly, but remains a perfect first strategy game for children.

From a Roman soldier scratching a grid into a pavement to a Cambridge computer playing a flawless game on a cathode ray tube, the history of tic tac toe is surprisingly rich for something you can draw in ten seconds.

Play tic tac toe free →

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