When AI was simple, debugging consisted of confirming that the character was simply doing the one thing you expected. Over time, debugging moved away from "what" and became more about "why?" or "why not?" The collision of information about the agents, the environment, the player and the game state creates an enormous amount of data that can affect the decisions that the characters make. In this presentation some features of ReView will be demonstrated as how it was used for debugging the multi-player bots in Killzone Shadow Fall.