This chapter is about designing and building playable levels for Dead Keys. More accurately, Dead Keys consists of multiple levels, and our focus in this chapter will be on the creation of one of those levels in detail. Only one needs be considered because the level-creation process is merely repeated creatively, after creating the first level, to produce all remaining levels at increasing difficulty levels. By level, I mean a scene in Unity terms-a complete and integrated 3D world where the game evolves according to its internal rules and logic. We'll look in depth at using and reusing modular assets, such as environment meshes, to build interesting levels of any size needed; we'll also see lightmapping and lighting overall to enhance realism, as well as NavMesh generation for artificial intelligence and Occlusion Culling for rendering optimization, among other issues. By the end of this chapter, we'll have constructed an integrated and atmospheric...