OXO was the one of the first digital graphical games to run on a computer, and was rather simple to use — the player played against the computer, with output displayed on the computer's 35×16-pixel cathode ray tube. The source code was short, yet played a perfect game of noughts and crosses. There is contention if it was the first digital graphical game. Another game, written by Christopher Strachey, created a version of draughts, was also run on the EDSAC in the summer of 1952. While the date that Strachey ran his program was documented, it is unclear when OXO was first played, so it is unknown which one predated the other.
This game provides examples of:
- Match-Three Game: You have to line three naughts or crosses up.
- No Plot? No Problem!: As it's only a simple tic-tac-toe game released in the 1950s, the plot is nonexistent.
- Unwinnable by Design: The computer never loses.
- Ur-Example: Depending on how you define a Video Game, this may be the first one ever, if you consider 1947's Cathode Ray Tube Amusement Device too simple and/or disqualified for lack of evidence of practical implementation. The next possibility is either the above-mentioned draughts game or Tennis for Two.