This paper presents an online training game for incident commanders to enact and create incident scenarios. The incident commander is the person in command on site when a rescue team is dispatched to a fire emergency. The challenge we are addressing in this work is to design a game and a game-based training process which can be used to support the change of work practice of fire fighters to become incident commanders (i.e. taking on a new professional role). The incident commander training game consists of two integrated parts: the IT artifact and the usage process. The two are integrated to provide necessary support for incident commander training via distance learning. The game is online and comprises three modules: The scenario player; the scenario creator, and; the log tool. The game and its pedagogical usage procedure are based on the theories of communities of practice and experiential learning. The novelty of this application lies in the combination of pedagogical theory and a specifically designed game. In comparison to other games for accident management training, the possibility for domain experts lacking of game design skills to create scenarios is an essential feature. Furthermore, the underlying fire simulation renders better "replayability" than a strictly branched scenario as the scenario creation is actually more of a process of setting conditions for the scenario than predicting each action of the player.