Geocast Games are multi-player video games played outdoors, using location-aware smartphones, that incorporate vigorous physical activity as an integral element. The goal of this project is to get video gamers, especially children, off the couch and playing outside in the park with their friends again. The key enabling technology allowing this style of game design is a scalable ad hoc wireless geocast protocol, invented in AT&T Research, for player-to-player comms. In this talk I will overview the GeoGames Architecture and the new research challenges it brings to game design. I will then describe three novel Geocast Games, iTESS, iTron, and Butterflies, each of which is implemented within my GC1 application suite, and some experiences having groups of children and adults play them using the GC1 prototype running on iPhones. If time, weather, and circumstances permit, interested attendees are invited to participate in an outdoor demo of the games.