Ghost AI

One thing that can enhance AI's performance is to have it imitate how a human player plays the game. This is one of human’s natural learning skills.

Ghost AI is an AI capable of imitating actions and playing styles of human players. It can use knowledge it has obtained from playing with a player to simulate that player's playing style. Other players can then play with the AI like they are playing with the player the AI imitates.

By replacing scripted AI with Ghost AI, players can be given a variety of challenges by fighting against computer controlled opponents who simulate other human players. A single ghost AI can even be created from 2 or more human players, allowing more variety in gameplay.

This type of AI has been used in famous commercial games such as the Tekken series, as in Tekken 5 Dark Resurrection, Tekken 6 and Tekken 6 Bloodline Rebellion. Players have been given an option to upload their Ghost AI files to the game's server so that other players can obtain these files and play against them.

Although the Ghost AI can address the predictability problem presented in the scripted AI, some drawback still remains. If trained by one person, the AI will imitate that person and will inherit not only his good moves, but also his weak plays. A method for solving this problem is to have several ghost AIs for the same character and switch between them during play sessions, or train the AI using more than one player. But each trained ghost AI will still have its weakness for players to exploit.    

Improvement is needed to create a more flexible and adaptable AI that can fix its weaknesses. However, Ghost AI is still an interesting method in creating an advance AI for the fighting game.

We had performed a research on the methodology of creating Ghost AI. The details can be found at this link.

Below are pictures showing the concept of our Ghost AI.