The fourth assignment is - not surprisingly - related to the world of Play. Participants should act according to game designers and the goal is to create a game design concept based on the previous two assignments. When a game design concept is reconciled with a model of reality and value proposal, the teams may experience tensions between the worlds and need to reconcile them.
To create a game design concept, teams have to blindly draw a game genre. The set of genres range from role-play to simulation. Adding this to what is already developed is quite a challenge and often hilarious (imagine if you draw religion as domain, physical skills as value, and rhythm game as genre) but also leads to amazingly creative and innovative ideas. Every time I'm surprised with what people come up with.