ABSTRACT

In the last couple of chapters, you have read about the hunter and infected AI from Naughty Dog’s third-person action adventure game The Last of Us. This chapter moves on to discuss the buddy AI.

The whole game focuses on relationships between characters and none more strongly than that of Ellie and Joel, the player’s avatar. Ellie accompanies the player throughout most of the game, and we needed the player to love her companionship. We were acutely aware of the common pitfalls with AI companions: the risk of them turning into a tedious “escort” quest, generally getting underfoot, or turning into mindless drones with no agency in the world. We had to make sure that Ellie never annoyed or frustrated the player and that she remained a compelling entity throughout the game. Most importantly, we had to build a character that the player cared for.