Location-based applications and services gain in importance as the spread of mobile devices equipped with GPS sensors and internet capabilities increases. Moreover, there is a trend towards customizable applications in order to let the user determine e.g. the content and the look and feel. Nevertheless, there exist only a few applications combining these features.

In this paper, we propose Gamework, a framework for customizable mobile location-based games as a specialization for customizable mobile context-aware applications and services. According to their programming skills players are able to adapt a game with Gamework. This can be done by changing the context, adding user-generated content, modifying the game-flow or implementing new games from scratch by reusing existing modules of the framework or adding new ones. Therefore our framework features a reuse-oriented development methodology as well as a feedback loop analyzing all accruing user-generated content. The results of this analysis are used to automatically optimize the game with respect to frequent user-feedback. Finally, we will transfer the results back to the more general area of mobile and context-aware applications and services.