Soft Computing

, Volume 21, Issue 23, pp 7005–7020 | Cite as

Procedural generation of non-player characters in massively multiplayer online strategy games

  • André Siqueira Ruela
  • Frederico Gadelha Guimarães
Methodologies and Application


This paper presents a coevolutionary framework for procedural generation of NPCs in MMORTS games. In this context, players need to defeat environmental troops in battle to gather resources and achieve their goals. The benchmarked game has several balance problems related to these battle activities, mostly caused by the handcraft design of complex game content. To solve this problem, the algorithm takes player modeled heroes as input and returns a solution evolved to win. By this way, the players need to think better in a new way to conquer the victory, adding new levels of challenge, keeping the game enjoyable. We present a new mathematical model to evaluate the solutions, based only on the number of soldiers on the input and output, making it easy to extend to other contexts. The results show it is possible to procedurally generate thousands of new efficient and fair builds, without violating the game rules. Moreover, our analysis of the results was able to identify unbalanced characteristics in the game design and we suggested simple way to fix it.


Procedural content generation Evolutionary algorithm Coevolution Massive multiplayer online (MMO) game Real-time strategy (RTS) game Video games 



The authors would like to thank to: Prof. Julian Togelius, for sharing his experience during the development of this paper. This study was funded by the following Brazilian agencies: State of Minas Gerais Research Foundation—FAPEMIG; Coordination for the Improvement of Higher Level Personnel—CAPES; National Council of Scientific and Technological Development—CNPq (Grants 30506/2010-2, 312276/2013-3).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.Graduate Program in Electrical EngineeringFederal University of Minas GeraisBelo HorizonteBrazil
  2. 2.Department of Electrical EngineeringFederal University of Minas GeraisBelo HorizonteBrazil

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