OXO is a pioneering computer game that simulates the classic game of Noughts and Crosses, commonly known as Tic-tac-toe. Developed in 1952, it stands out as the earliest game to feature visual output on a video monitor. The game was designed to be played on the EDSAC computer, utilizing a rotary telephone controller for player input. The visuals are displayed on a 35×16 dot matrix cathode ray tube, providing a glimpse into the early days of computer graphics.

In OXO, players engage in a challenging match against an artificial intelligence opponent, making strategic moves in an attempt to align three symbols in a row. As a full version game available on Windows, OXO serves not only as entertainment but also as a historical artifact that showcases the evolution of gaming technology.