Intelligent AI design

As game makers can probably attest, one of the biggest challenges of creating a good first-person shooter is the artificial intelligence development. Programming an AI-controlled bot to perform with enough skill and unpredictability to convince you it’s a real opponent is a tremendous feat. In fact, I don’t believe any modern shooter has produced artificial intelligence that would pass the Turing Test (a thought experiment where a computer persuades a test subject that it is human). Even with the relatively advanced AI in games like F.E.A.R. and Crysis, at no point during those gameplay experiences was I fooled into believing that the enemy soldiers I mowed down were anything more than automatons navigating a scripted path with limited awareness of the environment.

But here’s a thought: do shooter NPCs need to have HAL-level brainpower? If my subconscious will never let me believe that a computer-controlled opponent is actually a human being, then there’s seemingly little point in a game developer designing uber-brainy AI. So what should a developer’s goals be when coding shooter AI behavior? That’s a question wholly dependent on one factor: whether the AI is made for a single- or multi-player game.

In a single-player shooter, bots don’t need to be equipped with an AI as smart or as skilled as you are—it’s more important that they be designed with “fun” AI. The goal shouldn’t be to put single-player bots on equal footing with the player. Most of the time you’re going to fight against more than one AI opponent, so it would be unreasonable if each bot was just as good as you. AI grunts serve as dynamic obstacles in a map—a scripted shooting gallery that fires back, which worked well in Call of Duty 4.

Perfect aim and the ability to dodge bullets actually hinder the illusion of “smart” AI. F.E.A.R.’s enemies had some flaws scripted in to make you feel like you’re not fighting your Core 2 Duo

And since level designers have full control of the environment, enemy placement can be arranged to give the illusion of intelligence by predicting how a player will progress through a map. For example, enemy soldiers in F.E.A.R. appear to astutely respond to calls for backup to flank your position. But those bots were actually already in place, waiting for you to activate them when you passed a specific point. The designers just placed the trigger to coincide with predetermined combat sequences—the soldiers would have “responded” and attacked even without any apparent cues. Bots don’t need to be smart; they just need to fake it.

On the multiplayer side, however, the purpose of bots is to simulate playing against a human opponent, and preferably one that’s just as good as you. If killing a bot is too easy, the game won’t be rewarding; but when it’s too difficult, it just feels like the bot is cheating with perfect aim. The same problem doesn’t exist with human opponents; I get plenty of fulfillment owning noobs and can respect a player that’s much better than me. It’s a fine balance—I want multiplayer bots to be “smart” enough for me to get the same satisfaction from defeating one that I would from winning an online duel, even though I don’t want them to be too good and dip into an “uncanny valley” of intelligence. Here, bots need to have “smart” AI so I can feel good about outsmarting them.

The biggest hurdle in AI design isn’t technical, but rather the player’s awareness that they’re playing against a computer. Player expectations have a huge impact on the gaming experience, and game designers should write AI that caters to (and takes advantage of) those preconceptions to make the experience both rewarding and fun.

September 23, 2008


  • Ravenbom - September 25, 2008 2:40 a.m.

    I'm with sourmoomoo95, can we stop with the 1st nonsense? It's sorta getting played out now. Anyways, I agree, AI needs to be more than just uncanny aim. BUT, in my opinion, first person shooters need to change shit up a little. After a few shooters, I feel like I might as well be on rails in the arcade, because level design is essentially on rails. It hasn't fundamentally changed in a LONG time. Give the AI a more open level design, rather than the typical linear setup, and it would be more apparent that AI needs to change. Metroid Prime games get away with poor AI in an open level design since it's not really clear you're supposed to be fighting intelligent life, except for boss battles, for the most part. Still, grunts are fine, and part of the fun. FEAR AI doesn't creep me out, it's a noticeable change in AI standards though. What would creep me out is if they had a bunch of coward grunts who begged for their lives when they were almost dead as you spray and pray and blow them away before you have a chance to consider mercy. Or if they gave up when you knee cap them. It also seems like real AI wouldn't just blindly charge forward, but then again, that's exactly what players have been doing for years. Still, it's almost like developers have acknowledged this, and write it into their stories, like in FEAR, all the soldiers are clones being mentally controlled, or Resident Evil(yes, not a FPS) they're zombies, or Metriod they're non-sentient beings, or Bioshock they're ADAM crazy mutants, and in STALKER you face toxic wasteland mutants. I'd be willing to bet that the next big FPS has you facing the same AI and same linear level design we've seen a hundred times already, only this time, it will be robots.
  • ELpork - September 24, 2008 8:46 p.m.

    I did not know that about F.E.A.R. and its AI..... I learned something today
  • JosephCh - September 24, 2008 7:17 p.m.

    Also, the articles aren't really that bad, and some can be pretty interesting. Sure, GamesRadar features tend to be much more entertaining, but I welcome any additional content to the site. And again, nobody's making you read these articles ;).
  • Skellington - September 23, 2008 11:54 p.m.

    SECOND!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! HECK YE...oh, wait... Deja vu...
  • Skellington - September 23, 2008 11:53 p.m.

    FIRST!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! HECK YEAH! This is my first first. And, yes most Ai is indeed terrible.
  • evilsanta23 - September 28, 2008 6:04 p.m.

    cool article. i agree that ai has to be bettr in a lot of games but not to good that they'll whope our asses.and can people stop the 1st 2nd and so on stuff? its imature. and i agree with u Schuutlz about the crysis ai but it can be incredibly stupid. if u tranqalize some1 while their talking to some1 else then sometimes the othr person will just keep on talking. and i once was runnin down a beach wen suddenly a enemy comes out of the watr sees me runs bak in runs bak out then runs bak in and dies lol.
  • Schuultz - September 26, 2008 2:29 p.m.

    I'm disappointed that he didn't mention Crysis at all! Ok, it didn't have the best AI, there were quite a few glitches to it, but one thing I really appreciated about it, was that the bots had "human mistakes" scripted into them. Sometimes, when they would leap over objects, they would trip and fall, or, if you panicked them, they would try to run away and maybe even run into another bot, and they would both fall. That's the kind of stuff that makes them feel somewhat real!
  • HypherionWing - September 24, 2008 8:57 p.m.

    "stop putting these pc gamer things here just put them in that crappy magazine" What kind of moron would be browsing the PC section on GR and insult PCgamer.... Kids these days. Decent article mind you, F.E.A.R AI always creeped me out on the harder difficulties.
  • sourmoomoo95 - September 24, 2008 7:46 p.m.

    OMG I like got the 8th comment i must be GOD lololololol its so annoying stop with the first stuff already
  • monojono - September 24, 2008 6:03 p.m.

    "stop putting these pc gamer things here just put them in that crappy magazine" No-ones forcing you to read them. Why don't you stop putting pointless negative comments on articles you're not intelligent enough to write.
  • cd41 - September 24, 2008 2:12 a.m.

    AI is so important in a game, for more realism than anything, its nice to dominate but nicer to get a challenge once in awhile
  • skyguy343 - September 24, 2008 1:42 a.m.

    THANK YOU!!! that is exactly what i keep saying
  • jojo13jojo233 - September 23, 2008 11:56 p.m.

    stop putting these pc gamer things here just put them in that crappy magazine

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