This presentation supports my paper at ECGBL13. The central idea to the presentation is that making serious games that are reliably able to achieve their goal is really hard. Good theory tends to be at a very high level, whereas game design happens on a day to day basis at a much lower level. We need procedures and processes that can help designers bridge the gap between theory and practice. Cognitive Walkthrough is a well established UI process that helps UI designers to correct their mistaken assumptions and biases by scaffolding their thinking - but there is nothing magical about UI design. All interaction design requires the designer to think "like" another type of user. So I'm arguing that we should adapt Cognitive Walkthrough to support our game designers, particularly serious game designers. I also present one adaptation of Cognitive Walkthrough and use it to evaluate why very similar sections of one educational game differed greatly in their success.