Ataxx

Ataxx (アタックス) is a strategy video game published in arcades by Leland Corporation in 1990. Two players compete on a seven-by-seven square grid. The object of the game is for a player to have a majority of the pieces on the board at the end, by converting as many of their opponent's pieces as possible. In a single-player game, the opponents are "bio-invaders from a different dimension."

The concept was invented earlier by Dave Crummack and Craig Galley for the unreleased 1988 video game Infection. Virgin Mastertronic licensed it to Leland as well as using the design in its own Spot: The Video Game released the same year as Ataxx. There are numerous independently-developed clones. Although Ataxx was sold as a video game and not with a physical game board, it can be played with a Reversi set.