In this design case, we report our design and playtest of a form of alternative reality, educational simulation that we call a playable case study (PCS). One of the features that make our simulations unique is how they are designed to implement a principle called This Is Not a Game, or TINAG, meaning that the affordances we design into the simulation suggest to students that the experience they are having is real, in contrast to the way the artificial nature of the experience is highlighted in many computer games. In this case, we describe some challenges we encountered in designing a PCS to align with TINAG, along with how the situation in which we play tested the simulation highlighted other ways in which the principle of TINAG was challenging to achieve.