Follow the Leader: a Scalable Approach for Realistic Group Behavior of Roaming NPCs in MMO Games

In modern Massively Multiplayer Online Games, Non Playing Characters (NPCs) moving on the battlefield play a key role in term of user experience: many time players are required – alone or in groups – to fight or avoid them in order to progress in experience. Unfortunately, standard NPCs behavior, i.e., patrolling between rally points, does not put a significant challenge to players once its deterministic movement pattern is discovered. This paper addresses the problem of defining a smart, more challenging, and natural movement model for NPCs. Getting inspiration from the kids’ game “follow the leader” we adopt Artificial Intelligence techniques such as behavior trees and blackboards to provide NPCs with changing paths, dynamic aggregation in parties, and tactical decisions. Following this approach, players’ experience will greatly improve thanks to an always-changing battlefield scenario.