AI, Game AI and apparent intelligences

A subscriber of Think Artificial wrote to ask me about games and AI. In short, DF asked what my thougths are on AI in games and which ones I think are the most intelligent.

To answer this bluntly: Game AI is very different from it’s non-game counterpart, and it’s not my field of study. I’ve only compared modern games through a window. However, Alex of AIGameDev has superb coverage of AI in games and the top AI games of 2007, by community vote. The top of the line are Half-Life-2.ep.2 and BioShock.

But regarding Game AI in general: modern games are horribly void of intelligence. It depends on where you set the bar, certainly. There’s tons of AI in modern games compared to 5 years ago. But the first thing to note is that Game AI is not the same as AI. It’s a subset of it. Just like discrete mathematics are a subset of mathematics. And moreover, Game AI is a very specialized subset—it has well defined goals, models for construction and limitations.

Games are governed by laws of commerce first, then innovation.

A game is governed by different laws than academic, general AI R&D. It’s a commercial product, and commercial products depend on older methods wherever possible—methods that have proven successful. Most (sane) business men do not put all their money on a new and untried idea because they don’t know if it will succeed. So, most of commercial products are bulked up with a lot of things that’ve been successful in the past and then leave a breadcrumb for innovation.

This is very different from academic AI research where the point is to do things that’ve not been done before.

Now aside from these drastically different goals of commercial ventures and academic ones, a game’s purpose is to entertain. As long as the player is entertained it doesn’t really matter what goes on under the hood. Because of this, there’s a certain witch hunt that takes place in the game industry:

A modern game developer is on a mission to slaughter innocent intelligent processes wherever possible.

A game AI developer tries as hard as he can (usually at the bidding of a project manager) to minimize intelligence. One reason is that intelligent processes are massive processing-power hogs. Thus, like an obese overeater the systems must forcibly give away every other meal to accommodate an average person’s desktop PC — and those machines don’t have much elbow-room to replicate the massive crimson jelly residing in the heads of animals. Human or other.

And then there are graphics, another obese overeater, who also need a place at the table. And because games are governed by the laws of commerce, Game AI must leave at least five chicken wings more than it ate itself for its obese, graphics rendering sibling. Beautiful games get a lot of coverage and attention, and developing graphics is a question of engineering. In a business plan it’s therefore rational to emphasize graphics. Both in terms of predicting the amount of effort required to implement it and the potential payoff.

Because of these severe limitations on how much processing power the intelligence is allowed, developers are forced to dumb-down the processing and make their AI appear intelligent instead.

To some it may not be clear what the difference is between making something appear intelligent and actually making it intelligent. After all, there has to be some amount of intelligence if something’s intended to keep its appearances. Right?

An intelligent system is expected to produce solutions to problems, uncertainty and often in complex situations. Appearances, however, are concerned with making an observer believe they are intelligent. To accomplish this in games the environment (the input to the AI) is kept controlled and limited. For a vivid example of this:

  • NPCs in games don’t use computer vision to perceive where the player is, instead they get fed (X, Y, Z) coordinates, giving the appearances of eyesight and visual processing capabilities.

The game designers tailor the environment and its limits to make sure that the intelligent processes can handle them, and vice versa. It’s the lifelike gatekeeper who doesn’t need to know how to find his way home because he has no home. It’s the terrorist that can pull a trigger but couldn’t count his fingers if you took his shotgun and held it to his head (and you can’t).

For a different and real-life example of appearances versus actual intelligence, to show how diversified the game AI “trickery” can get:

  • The developers of Halo 3 found a correlation between how smart the AI was and how tough it was. If they made the NPCs smarter the game became tougher. If they increased the health of the NPCs, making them tougher, the human players perceived them as more intelligent.

Halo 3 screenshot

The first rule of AI in commerce is that you don’t talk about AI in commerce

Like I’ve stated in another post, the gaming industry is pretty much the only industry that dares market products using the term artificial intelligence. The reason for that is complicated and I won’t talk about it from all perspectives. But what I will tell you is that its partly due to people knowing what to expect from games.

The gaming industry builds from the sets of platform resources and devteam innovation. These are sets that the consumers know. It’s the set that the elite gamer knows because he understands the nature of programs and what the required Hz’s actually stand for. And it’s a set that the average gamer knows because he’s fought space aliens so many times that he’s learned what they’re capable of. With consumers that know what to expect, the term can be used without people boiling a can of hype.

In contrast, Academic AI builds with a set that appears to the consumer as one of infinite possibilities: Because people don’t know (exactly) how the mind works, they/we can’t evaluate how far we are from recreating it in machines. It’s unknown. And because the average consumer can’t accurately evaluate the unknown, it doesn’t matter if yesterday’s AI was primitive; most will still anticipate it advancing leap-years overnight. Just like kids in the backseat of a car asking if it’s: “human now? it must be human now? how about now?“.

Thus, when the term AI is used in areas where the limitations and previous products don’t foretell the nature of the next, people start imagining Terminators all over again. And then they get incredibly disappointed when they realize all the AI can do is answer questions about farm animals. (And only when you begin a sentence with “What is…”).

That’s obviously not a scenario a businessman would like to encounter, so it’s best just to focus on something else when marketing, like Apple does when presenting its operating systems to the public.

In summary

Game AI is just one of many different subfields of AI and is governed heavily by the laws of commerce, entertainment value and modern desktop computing resources. While it may seem it must intersect with other subfields, the truth is that its a somewhat isolated field with its own sets of tricks and tools. (Mostly tricks.)

At times, games may also feel like they are the only commercial products successfully employing AI. But this is largely because of too high consumer expectations to AI in other products, and the consequent fact that companies don’t like mentioning that their product uses, what is by definition, artificial intelligence.

And finally, a difference between apparent intelligence and actual intelligence is that the latter figures out solutions to problems, while the former doesn’t care about what happens under the hood as long as an observer thinks it’s intelligent. A lot of the times—that doesn’t involve intelligence at all.

Links & references


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7 Comments, Comment or Ping

  1. Interesting article, but I think you’re greatly overemphasizing the role that processing power plays in the use of AI in games. In most cases, the factors that determine the quality of a game’s AI tend to come into play long before an AI system is developed enough to measure its performance.

    There are some games, such as real-time strategy (RTS) games and massively multiplayer games (MMOs), where AI performance is a major issue due to the need to simulate massive numbers of AIs and players in real-time. In most other cases, though, when you hear developers say things like “We don’t have enough processing power for better AI,” it’s much more likely to be a disingenuous excuse. The real reasons usually have much more to do with the other factors you mention in your article.

    > A game AI developer tries as hard as he can (usually at the bidding
    > of a project manager) to minimize intelligence. One reason is that
    > intelligent processes are massive processing-power hogs.

    You’re somewhat correct that much of the industry intentionally avoids deep AI, and that there’s a strong culture of “AI avoidance” in some parts of the industry — an attitude that used to make a lot of sense, but less so as the industry matures.

    Done correctly, intelligent processes don’t need to be massive processing-power hogs. We can do a lot more with the processing power we already have, even before we go anywhere near what’s generally referred to as “academic” AI techniques.

    I’m planning to post on this subject at http://www.ai-blog.net/ in the future.

  2. In most cases, the factors that determine the quality of a game’s AI tend to come into play long before an AI system is developed enough to measure its performance.

    Hi Paul. I see what you mean — I think you misunderstood me, but to roll with it: This is when we’re speaking in terms of a minimalist-AI mindset, yes? If we were to apply the same extravagant, detail- oriented thinking to AI as is applied to graphics in modern games, then we could most certainly push the limits.

    What I meant was to clearly point out that game AI involves shortcuts around the heavy processing. For example, object recognition can be implemented with machine vision techniques to simulate the processes in natural beings — but in a game you can (and probably will) simply maintain a list of object names instead. In that sense intelligence is a processing power hog, but today’s game AI dev involves finding ways around it. And like you say, if it’s done right it doesn’t need to suck power.

    I’m planning to post on this subject at http://www.ai-blog.net/ in the future.

    Thank you for the insight Paul. It’s fantastic to hear it directly from a professional who’s worked on major league games. I look forward to reading your entry when you post it.

  3. DF

    Great post!

    Here are some of my comments about bringing “Real AI” to gaming:

    1) It may not be as fun as “Game AI” In a comercial way, but It does provide other types of fun (not better, different).

    2) I agree It Isn’t necessarily more processor/memory expensive. Either way, I don’t think technical issues are relevant to the general concept and the discussion about bringing better AI to games specially considering how fast the processing power increases. Besides, this can be dealt with In a variety of ways – the same way 3D games use “tricks” like smart textures, fog and variable-poly-count , AI also benefits from this kind of design philosophy.

    3) It Is more expensive for the game companies, but maybe It’s a price certain consumers are willing to pay. Personally, I’d trade all the graphics In Bioshock for better AI.

    4) Usually when people think about AI In Games, genres like Action, strategy and RPG come to mind. Although these kind of games deal with lots of relevant AI issues, I dont think they should be the main examples on discussions about “AI in Games” (as they clearly are nowadays). All types of games could benefit from exploring other kinds of “intelligence” (not necessarily more complex or complicated), that are not found In these genres.

    Everybody who plays action games knows that, no matter how smart NPC’s are, sometimes they do VERY stupid things (like keep running towards a wall, getting “stuck” forever in a tree, not noticing you are behind him even though you are on a noisy terrain…moving fast… shooting… with a tank, etc). The reason Is that AI In these kinds of games Is applied to specific aspects of gameplay, resulting In a very specialized and limited intelligence – and this Is intentional.

    In most action games players dont want soldier #92 to run slower because he Is sad for the death of soldier #23, for example – the focus is on battle/strategy, not human relationships. And that’s exactly why I think that, by using this kind of game (or any other specific genre for that matter) as a “reference for AI In games”, this simplifies a very interesting subject that deserves more attention. In AI-GAMEDEV’s list, for example, the top titles are action/strategy games, even though they represent only a very specific usage of AI. I also I noticed some people mistake “cool 3d graphics” and “fun gameplay” with “good AI”.

    I have NOTHING against fun and beautyful games with poor AI (or even no AI), but I do think this kind of confusion somehow helps to keep AI “hidden”, not only from programmers, researchers and gamers interested In this field, but also from the gamers that don’t even know about It and still think AI Is “when the ogre runs away instead of shooting”.

    5) I hope games get more and more independent from the “laws of industry”. Some of the greatest examples of innovation In games are In research, independent and experimental projects. Still, I know there are games with great AI out there (In many genres), and from time to time I do find great stuff (both old and new).

    I think It would be a good idea to have an updated list on-line with these titles, not only for research purposes, but also to spread the word about the advances and possibilities of AI In Games to the general public. I know of some resources on the web, but they are usually about specific genres (strategy, interactive storytelling, etc) and lack updates. Maybe some AI blog could host It? :)

    Meanwhile, if you have any links/suggestions, please post them here! I have some links of my own. If anyone Is interested, I can post them also.

    That’s It! I hope I made some sense. Though I am a Computer Engineer, my research field Is on Art and Technology so I’m probably out of my league here.

    Also, I’m brazilian and I dont write In English very often, so I hope my writing Is understandable :)

  4. Some great points there DF.

    I have NOTHING against fun and beautyful games with poor AI (or even no AI), but I do think this kind of confusion somehow helps to keep AI “hidden”, not only from programmers, researchers and gamers interested In this field, but also from the gamers that don’t even know about It and still think AI Is “when the ogre runs away instead of shooting”.

    Agree that while graphics get so much attention it draws commercial pressure away from AI dev. This is no single person’s fault or decision of course, it’s the zeitgeist. But as graphics get closer to realism and processing power increases, people will move on to other aspects of gameplay, and I think we can be fairly certain that AI is near the front of the line (along with innovative machine interfaces, like Nintendo showed recently). Like Tozour said, avoiding game AI is a mindset that makes less sense as the industry develops. Let’s hope the business-oriented make sense of that soon ;)

    I know of some resources on the web, but they are usually about specific genres (strategy, interactive storytelling, etc) and lack updates. Maybe some AI blog could host It? :)

    It’s possible—but perhaps Wikipedia would be a better venue? Possibly a list page linked to from the Game AI page.

    Meanwhile, if you have any links/suggestions, please post them here! I have some links of my own. If anyone Is interested, I can post them also.

    Feel free to post!

  5. They should just call it AAI.

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