Evaluating your content generator is a very important task, but difficult to do well. Creating a game content generator in general is much easier than creating a good game content generator-but what is a "good" content generator? That depends very much on what you are trying to create and why. This chapter discusses the importance and the challenges of evaluating content generators, and more generally understanding a generator's strengths and weaknesses and suitability for your goals. In particular, we discuss two different approaches to evaluating content generators: visualizing the expressive range of generators, and using questionnaires to understand the impact of your generator on the player. These methods could broadly be called top-down and bottom-up methods for evaluating generators.
I created a generator, now what?The entirety of this book thus far has been focused on how to create procedural content generators, using a variety of techniques and for many different purposes. We hope that, by now, you have gained an appreciation for the strengths and weaknesses of different approaches to PCG, and also the surprises that can come from writing a generative system. We imagine that you also have experienced some of the frustration that can come from debugging a generative system: "is the interesting level I created a fluke, a result of a bug, or a genuine result?"Creating a generator is one thing; evaluating it is another. Regardless of the method followed, generators are evaluated on their ability to achieve the desired goals of the designer (or the computational designer). This chapter reviews methods for achieving that. Arguably, the generation of any content is trivial; the generation of valuable content for the task at hand, on the other hand, is a rather challenging procedure. Further, it is more challenging to generate content that is both valuable and novel.