The joke goes something like this: if interaction designers had made Super Mario Brothers, the game would just have one large button labeled “Rescue Princess.” There is some truth to that. Interaction designers strive for products that let people get tasks done quickly and easily. Yet, the fun of gameplay is overcoming challenges and rules deliberately set to impede a player’s progress. So as interaction designers, how do we separate challenges that add to the gameplay from those points of frustration which detract? For game developers without access to interaction designers or researchers, the challenge can be even greater. When developing a new game, what general principles should be followed to make sure it remains safely on the fun side of frustrating? Jakob Nielsen gave us the ten canonized Usability Heuristics for web and system design; our humble goal is to do the same for computer games. This presentation will provide ten interface heuristics applicable to games as well a few useful “discount” evaluation techniques for when you don’t have the time, or the money, for a full lab study.