The final part of the book discusses atmosphere and immersion from a storyline's standpoint. To summarize it, it's the culmination of everything that the book discusses in the previous chapters. All the discussion about light, textures, geometry, architecture, gameplay and sound is made from a technical point of view. In this site I've given many many examples about atmosphere and storytelling.

One last comment that Hourences made is that multiplayer levels can and should have storylines, in contrary to what lots of people would say. This is really hard to achieve because multiplayer levels have different goals. One example would be Bioshock 2. The multiplayer part is not just a bunch of multiplayer levels detached from the single player storyline. They took some effort to explain that the players are placed during a time period of a civil war that is part of the Bioshock's universe. Another example would be Movie Battles II, a mod for Jedi Academy that attempts to bring the battles seen in the movies to the game. Allowing the players to experience events from the movies by playing them. This is a very hard task to successfully accomplish because we have different demands for single player and multiplayer. Different weapons, different settings and different perspectives.

The extras in the book are interviews and some in depth analysis of Hourence's own levels.