ICT provide opportunities to improve organizational performance. However, many organizations still struggle with integrating new organizational structures, new work practices and ICT, because information systems (and other tools) that support organizational work processes are embedded in the existing culture and work practices. The adoption of ICT by an organization is a complex interaction between task-, technology-, group internal system-, and organizational context factors. Organizational prototyping helps to develop ‘embedded’ information systems. It involves managing a dual process of both adapting the tool to the organization and adapting the work practice to conditions of the tool. In an action research study at the Amsterdam Police Force we developed two simulation-games that served as ‘organizational prototypes’ and supported the analysis and improvement of coordination practices and the integration of (new) ICT in these coordination practices. The first game has been played 9 20 times with 8-15 policemen; the second game has been played 2 times with a similar number of policemen. In this paper we reflect on the design of the games. We explain how and why we have dealt with issues like for instance complexity of the game, number of players, degree of realism, amount of time for reflection, time pressure, et cetera. Next we show the impact of these design choices for the game execution and game results. Finding the right balance between realism/validity on one hand and not too much complexity on the other hand proofs to be the major design challenge. Furthermore some surprising results were that distributed work can perfectly be simulated in one location, that computer support does not distract from learning objectives when the technology functions properly, and that time constraints may inhibit learning.