Designing digital games is primarily interaction design. This interaction manifests as a meaningful change in the game world. An aspect of a game can only change dynamically with a parametric model of this aspect available. One aspect of digital games is yet missing such a systematic description: the genre of a game is currently only determined by its designer. This paper introduces a new approach that allows for dynamic blending between genres. We describe a set of game mechanics that express the characteristics of different game genres. We extract a parametric model from these mechanics to allow dynamic blending. The paper illustrates the possibilities of this approach with an implementation of a multi-genre-game. It also provides empiric evidence that the described model successfully generates different game genres.