A game AI general theory has been researched and developed in game industry in the world, and a new game AI general theory of AI in digital game is supposed with three AIs. For a large scale of game, a game AI system consists of three types of AI such as meta-AI, character AI, and navigation AI. A meta-AI is to control a game dynamically from a bird-view by watching a player’s behavior. A character AI is a brain of a game character such as a buddy, a monster, or a villager to make a decision in real-time. A navigation AI is to recognize an environment of a game to find a path or a best location to move dynamically. Especially, character AI is a main topic to study in game development, and it includes many fields such as multi-layered structure, character animation, agent architecture, decision-making modules, and so on. A new method of decision-making of combination of behavior trees and state machines is supposed. It is called AI Graph. The game AI general theory was applied to an AI system of an action-RPG game “FINAL FANTASY XV”. The results are showed in the paper. All characters’ decision-making system in FINAL FANTASY XV are based on AI Graphs. An AI Graph Editor is a tool to make an AI Graph only by using a mouse and simple text inputs. A dynamics of the new method is showed by explaining AI Graph Editor precisely.