This paper describes the design, implementation, and initial testing of a reusable platform for the creation of pervasive games with geo-localization services. We concentrate on role-playing games built by combining several types of simpler mini-games having three major components: Quests; Collectables; and Non-player characters (NPC). Quests encourage players to be active in their physical environment and take part in collaborative play; Collectables provide motivation; and NPCs enable player-friendly interaction with the platform. Each of these elements poses different technical requirements, which were met by implementing the gaming platform using the inTrack pervasive middle-ware being developed by our group. Several sample games were implemented and tested within the urban environment of Kyoto, Japan, using gaming clients running on mobile phones from NTT DoCoMo, Japan’s largest mobile provider.