This game was developed when I was part of the Geogames project at the Chair for Computing in the Cultural Sciences at the University of Bamberg: http://geogames-team.org/
“In the classic board game two players set their markers – normally X and O signs are used – on a 3×3-square game board. Whoever manages to set three of his markers in a column, row or diagonal line wins the game.
GeoTicTacToe adopts these rules but transfers the game play into the real world. The spatial version of the game board consists of nine locations (GPS coordinates) found in the real world game area defined by the organizers of the game. Additionally two starting locations for the two players have to be defined. In contrast to the original game players of GeoTicTacToe do not set their markers in a consecutive order. The game is played in real-time, so that a player can set two or more markers before his contrary manages to set one of his own.” (1)
(1) Schlieder, C., Kiefer, P., and Matyas, S. (2006). Geogames – Ortsbezogene Spiele als neue Form des Edutainment, In: i-com: Zeitschrift für interaktive und kooperative Medien, Volume 5, Issue 3/2006, ISSN 1618-162X, pp. 5-12.