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/
“CityPoker is played by two players (usually two teams) that start with a given poker hand and move around in an outdoor environment to find cards hidden in caches in order to improve their poker hand.
The caches are five geographic locations each hiding two cards. GPS is used to find the caches. The players get a map of the area showing five large rectangular regions which contain the caches. Each of these cache regions is defined by a pair of imprecise geographic coordinates. Precision can be increased if a multiple choice quiz is solved: ”Cache 1 is located at N 49◦ 53,XXX – E 10◦ 53,YYY. Get more information by correctly answering the following question. Which pope is buried in Bamberg cathedral? (a) Clemens II, XXX=535 YYY=595 (b) … (c) …”’ If a team cannot answer a quiz either by the team members’ knowledge or by asking someone on the street they will have to search all three possible locations for a cache. Because of the inaccuracy of the GPS localization method, an additional perceptual hint for the location of the cache is provided such as:
”The cache is under a big tree”. Each team may select one out of the two cards at every cache but a team may not visit a cache twice. CityPoker is a perfect information game which means that at any moment in time each team knows which cards the other team possesses as well as which cards are hidden in which cache. This implies communication between teams and is one of the reasons why it is attractive to design a CityPoker assistance system running on smartphones. When a time limit is exceeded (e.g. 2 hours) the game ends and the team with the best poker hand wins. The game is played with a set of 20 cards: Ace, King, Queen, Jack, and 10 in the four suits spades, hearts, diamonds, and clubs. The winning order of the final poker hands is as follows: Royal Flush, Four of a Kind, Full House, Straight, Three of a Kind, Two Pair, and Pair. CityPoker rules do not rank the hands by suits so that a draw is possible.” (1)
You can read more about CityPoker in German in this article from DER SPIEGEL 32/2007 (http://www.spiegel.de/spiegel/print/d-52485441.html) – PDF: Geogames_Spiegel_2007.
(1) Kiefer, P., Matyas, S., Schlieder C. (2005). State space analysis as a tool in the de- sign of a smart opponent for a location-based game, In: Masuch, M., Hartmann, K., Beckhaus, S., Spierling, U., Sliwka, F. (eds.): Proceedings of the Computer Science and Magic 2005, GC Developer Conference Science Track, Aug.16-18, 2005, Leipzig, Germany, Messe Leipzig, ISBN 3-9804874-3-1.