also known as tic-tac-toe. In case there is anyone on the planet unfamiliar with this game, it is played on a 3 × 3 grid, with players taking turns to add their symbol – an X or an O – in one ...

[Circuitchef] used gates and a few flip-flops to build a two-player electronic Tic-Tac-Toe game ... The board is arranged in a 3×3 matrix of momentary push buttons and bi-color LEDs.