Open Coverage

On the AI Strategy for KILLZONE 2’s Multiplayer Bots

Alex J. Champandard on March 8, 2010

The first session at GDC's AI Summit features a case study of recent games. This post contains all the references from my presentation about KILLZONE 2's multiplayer bots, and specifically their AI strategy. The project was done under the expert supervision and guidance of Remco Straatman (Lead AI Programmer) along with Tim Verweij, who also established the architecture as part of his thesis. Here's the presentation itself:

On the AI Strategy for KILLZONE 2's Bots
Alex J. Champandard, Remco Straatman, Tim Verweij.
Download FILE

The rest of this post contains all the references from the talk itself, including work and presentations by Arjen Beij (Senior AI Programmer), Michiel van der Leeuw (Technical Director), and William van der Sterren. Most of these references are available freely, either as a public download or for Insiders (free registration). If you'd like to go into more details, see the the full video recordings as part of the Premium Area.

Individual AI

For details about the combat AI for individual humanoids based on KILLZONE 1's technology, see the talk from the Game Developer's Conference 2005:

Procedural Combat Tactics (Paper)
Remco Straatman, Arjen Beij, William van der Sterren
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Procedural Combat Tactics (Slides)
Remco Straatman, Arjen Beij, William van der Sterren
Download PDF

For details about the AI as it has evolved on the PS3 and SPU, see these extracts of the talk by Michiel van der Leeuw:

These are Insider articles and include a video of the technology.

Architecture & Planner

For details of the overall architecture, see Remco Straatman's part of the presentation at the Paris Game AI Conference 2009, which is based on Tim Verweij's thesis work:

Killzone 2 Multiplayer Bots
Remco Straatman, Tim Verweij, Alex Champandard
Download PPT or PDF

Terrain Reasoning & Pathfinding

For more information about the processing and analysis of terrain, then finding a balance between automation and manual annotations, see this report with Kevin Dill, Sergio Garces, William van der Sterren and Paul Tozour.

The automatic area generation is based on a clustering algorithm. William van der Sterren's work is the best reference on the subject. There's also an implementation in the Sandbox that you can see in action here:

The squad pathfinding is derived from my master's thesis, though with some improvements since this publication:

Realistic Autonomous Navigation in Dynamic Environments
Alex J. Champandard, 2002.
Download FILE

The algorithm is essentially a hybrid combination of Dijkstra and Bellman-Ford-Moore.


As a reference for the squad and objective assignment logic, see this talk at GDC 2008 by Damian Isla:

Building a Better Battle: The Halo 3 AI Objectives System
Damian Isla, 2008.
Download ZIP Archive

For more information how different that was in KILLZONE 2, see the details in the recording from the Paris Game AI Conference 2009:


In this case and in general, strategy is more than the sum of its parts. Individual components of the system are relatively straightforward, well documented, and easy enough to implement. However, its their combination that make the overall result much more dynamic and involving to players.

If you have any similar experiences working on the AI strategy in your game, or have any questions about the technology in KILLZONE 2, don't hesitate to post a comment below.

Discussion 2 Comments

bubman on March 24th, 2011

the first pdf is a self-link :) interesting article, please correct it!

takuan on October 14th, 2014

The link to the paper "Realistic Autonomous Navigation in Dynamic Environments" is broken, unfortunately. I was quite interested in reading that :-)

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