In the previous chapter, we discussed the overall design philosophy and the AI techniques behind the Infected. In this chapter, we will discuss a question that relates to the human opponents in The Last of Us. When we started prototyping the human enemy AI, we began with this question: How do we make the player believe that their enemies are real enough that they feel bad about killing them? Answering that one question drove the entire design of the enemy AI.
Answering that question required more than just hiring the best voice actors, the best modelers, and the best animators, although it did require all of those things. It also required solving an AI problem. Because ...