Hi, the guide comes already pretrained on movie scripts - it is used to generate text responses to whatever the player says.
As for when it comes into play - the game has puzzles where the user has to solve by speaking/typing. If user input is detected to be in the context of the puzzle, the guide gives a scripted speech and moves on to the next puzzle prompt. If user input is detected to be outside the puzzle (e.g., free form chatting) then the answer by the guide is generated by the AI and the user can continue chatting on any topic of their choice.