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Age of Empires
Behind the Scenes
Bruce Shelley
Tony Goodman
Dave Pottinger
Bruce Shelley
"The AI will also learn your style of play as you replay the same scenario over and over again, and will pick up your general tendencies as you play the game."
Strategy +, August

DDave Pottingerave Pottinger

Dave on Dave:
I'm the Engine Lead and AI specialist for Ensemble Studios. I have a terrific wife of one year by the name of Kristen. I'm a 25 year old graduate of the University of Arizona with a computer engineering degree. I spend most of my time working; free time is spent relaxing with my wife, going to movies, and working on our house.

Games Web: In most real-time games, the emphasis has been on multi-player play versus the single player experience, and thus, the AI has suffered. What has Age of Empires done to improve the single player experience in terms of the AI?

Dave Pottinger: The simplest answer is that we have spent almost a year of development on the AI and given it a very high weight (in terms of time and effort) compared to other tasks. We've also picked a couple of key areas such as tactics and varied strategies to focus on. This focus allows us to concentrate on making those things jump right out and grab the player's attention (hopefully as a crushing herd of war elephants rumbles through a human player's town:).

Games Web: Did you address the computer AI and the unit AI separately?

Dave Pottinger: Yes. The UnitAI is exactly the same for the human and computer units. We did this to help reinforce the concept that we didn't want to cheat. The computer player interacts with the game in exactly the same way as the human player does. The UnitAI was completed first in order to let us play multiplayer games (for design and balance reasons); the computer player AI was started after the UnitAI was stable. The computer player also went through a comprehensive design process that has paid us huge dividends.

Games Web: How sophisticated in the AI, does it learn?

Dave Pottinger: It's really pretty sophisticated. It does learn about the scenarios it plays and also learns player tendencies (so it should improve over time). The tactics were probably the hardest thing to get right; we had to make the tactical AI module a lot more complicated that we originally thought in order to get it up to the level of the human player (we ended up going through three totally different models before finding one that clicked).

Games Web: A major weakness with the computer AI in games is that they cheat, is this the case with Age of Empires?

Dave Pottinger: This is a tough question; we've debated the issue extensively. Our primary focus for the AI is to have it create the best single player experience on the market. As such, cheating is secondary to that. Our goal is not to cheat, but we will if we need it to create a better game. We are getting closer to our goal everyday, though. The only way that we have to cheat right now is to give the computer player a resource boost at the beginning of the game. As we make improvements to the AI, we are able to reduce that boost. We should be able to remove the resource handicap on all but the hardest difficulty levels.

Games Web: Does you computer controlled units maintain formation in combat? Also, do individual units cooperate with each other?

Dave Pottinger: Yes, we have what we call a playbook. The computer player has a ton of plays that he can choose to run (simple frontal assaults, multi-front attacks, formation attacks, protection formations, etc.) from all directions on the map. It's a fantastic thing to see the computer attacking with catapults and protecting those catapults with infantry. The unit cooperation is achieved with a hierarchical combat model. Grouped units have a unit commander that runs the combat for that group. If a unit runs into trouble, he'll report to his commander for help. If the commander's group needs help, he'll ask the computer player to send more forces over.

Games Web: What else about the AI do you find worth noting? What makes it different or unique?

Dave Pottinger: We've attempted to do a complete AI that handles all phases of the game. I think the major differentiations will be the tactics, strategies, and the emphasis on not cheating. To play a game and have the computer build completely different units than the last time and use them in a different way is a great thing to see.

Games Web: What's the most challenging part of what you do?

Dave Pottinger: At this point, it's time management and execution. There are so many areas that I'd like to spend my hours on: there are always a ton of features to add to a game or an engine, the engine is never quite fast enough, the game designs change as the product evolves, the AI can always handle one more situation, etc. Deciding which items are most important and which deserve time is critical. Even more critical is an accurate, successful execution of our effort.

Games Web: As technology advances, multiplayer games are more and more involving, where do you feel that computer-based games are headed?

Dave Pottinger: I see a big shift in two areas: the real expansion of the massively multiplayer games and the resurrection of the adventure and role playing genres. Massively multiplayer games have been around for a long time, but recent technology is allowing us to do a lot of fun things (persistent games with a 100K players, etc.) that will really open up the games to huge audiences. I think the industry rotation is also coming around to role playing and adventure games again. New technology like speech recognition/synthesis and improved AI will play a big role in these, I think.

Games Web: Was there a particular point in your life where you realized that you were definitely headed towards game development?

Dave Pottinger: I did some "time" at a large computer company -- not MS:). I hated every minute of it and decided to do something fun; so I started a game company. That never really took off, so I joined Ensemble Studios last year and have been happily busy ever since.


The death animations rock!

The problems of victory are more agreeable than the problems of defeat, but they are no less difficult.
-- Sir Winston Churchill (1874-1965), British statesman, writer. Speech, 11 Nov. 1942, House of Commons. From The Columbia Dictionary of Quotations: Copyright (c) 1993, 1995 by Columbia University Press.