Thief 3: Emergent (Mis)behavior

By Shamus Posted Thursday Mar 30, 2006

Filed under: Game Reviews 23 comments

While playing Thief 3 some more I had a rather amusing AI mishap: A couple of NPCs went absoloutely sideways and started killing everyone.

All that glitters is not gold. Some of it is money and gems.

The setup was this: I’m in some guy’s jewelery shop, minding my own business and robbing the place. Then the owner gets home, and a couple of big goons are with him. From the sounds of it, he was involved with some underhanded deal with these guys and he tried to cheat them. He was supposed to hang on to some gems for them, but he was “skimming” the gems by (I think) cutting them. I don’t know. The goons are quite upset. The jeweler is unarmed and in a bad way. He’s trying to talk his way out of things and he’s not doing very well.

The conversation seems to hint that I might want to intervene. One of the goons says, “Sorry, but now we gotta kill ya. So unless you gots any friends hidin’ around here, this is it for you.” Odd thing to say. I can only assume this is the game’s way of suggesting I might want to help this guy, but I’m not going for it. If you make a deal with dangerous criminals, cheat them, and then get caught, then you deserve whatever fate you get. From my hiding place in the shadows I could drop one of the goons with an arrow, but then the other one would come after me. That is just too much trouble to save the life of a moron.

As the goons kill the jewler, he starts screaming for help. I decide to clear out. As I’m backing out of the room I bump something off a shelf and make some noise. The goons hear it and start hunting for me. An open doorway leading outside is on the opposite side of the room. I can’t make it there without the goons seeing me. However, I do have a noisemaker arrow, which is sort of a string of firecrackers on the end of an arrow. It draws the attention of people nearby. The goons are about to discover my hiding spot, so I fire the noisemaker out of the room. They hear the loud noise and go charging out into the streets…

…where they proceed to go completely nuts. They charge into the intersection outside and start slaughtering peasants in the street. The game auto-generates street traffic, so as they kill someone a new citizen is created nearby. (This happens off-screen, I never see them appear) This provides a steady stream of victims for the two killers.

My character is great at stealth kills, but nearly helpless in a stand-up fight. One town guard is usually more than I can handle. But these two guys are big, strong, and carry big swords. Whenever a member of the city watch shows up to help he just ends up on the growing pile of bodies. These guys are unstoppable.

I didn’t think to get a picture while this was going on, so the screenshot doesn’t really give the full effect. Whenever I look away the game does a bit of cleanup and removes some of the older bodies, so the pile is never bigger than five or six people. However, the real death toll must have been a few dozen. These guys were at it for a long time.

What a mess.

I’ve been thinking about this, and I’m still not entirely sure what made these guys go on the killing spree. Obviously it could have been a bug or a fluke or sloppy scripting, but I’m more inclined to think that the peasants that brought this on themselves, as the result of a chain of various behaviors. I obviously don’t have the source code, but I think that peasants become fearful when they see a character who has recently killed someone. (This is usually the player.) When they become scared they say things like, “I’m going to go find a town guard!” Then they run off to tell a guard about the actor that scared them. The guard will come and attempt to kill that actor.

Perhaps the noisemaker brought some peasants and the goons together, the peasants got spooked and decided to fetch the guards, which obliged the goons to kill them. Once this got started it would have fed on itself, since new peasants would get spooked by the pile of corpses in the street and forced the goons to kill them as well. If this is what happened then it’s an amusing case of unwanted emergent behavior.


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23 thoughts on “Thief 3: Emergent (Mis)behavior

  1. I’ve read that when they were doing the CGI for “Return of the King” for some of the huge battle scenes, it was completely impractical for them to manually animate all the orcs, so they created an AI routine to handle their behavior.

    Problem was, the orcs kept routing. Every once in a while, for no reason they could discern, their AI routine started shouting “Run away! Run away!” and all the orcs did.

  2. Dan says:

    Another reason for this behavior although less likely, is that when the “goons” ran into the street to find the noise that brought them there they assumed the civilains were the cause of the noise and the person or people that they needed to kill.
    One other posibility is that they are programed to kill any peasants that see them doing their evil crimes. I don’t know if my following suggestion is even plausable within the boundrys of the Thief game, but try coaxing a peasant to walk in on the murdering of the jeweler. The goons might then kill him/her. This would show that the goons were behaving outside just as they would have inside Only with a much bloodier and gruesome outcome

  3. Shamus says:

    Interesting observations. Both of your suggestions are very plausible, from what I’ve seen within the game.

  4. Dan says:

    Try killing the jeweler yourself and see how the thugs react. they will probably just try and hunt you down or they might call it a job well done, leave and ignore the mysterious arrow that killed their target.

  5. Shamus says:

    Wow. Brilliant.

    Dangit – I saved over that point of the game. If I want to try this, I have to start over at the beginning. Hmmmmm…..

    I only have toi do one mission to get to the point in the game where I can wander about the city freely, so I can visit the jeweler. Normally that one mission takes about an hour or more of sneaking about a large castle. Now I want to try something new:

    What if I just run all over the castle like a madman? I know where the key items are to complete the mission. What if I just plow through, sprinting. I bet I’ll end up with a parade of guards running after me.

    Should be good for a laugh.

    Then, I’m off the jeweler and see what happens.

  6. smapdi says:

    The goon/jeweler conversation is supposed to clue you in to the location of the hidden jewels, which are not in the jeweler’s house. Rather than following that story arc, I found that it is much more fun getting the characters on that level to go amok, and then just go pick up the jewels – the storyline doesn’t trigger their appearance, they’re there all along.

    You can also get the criminals to attack the guards, the guards to attack the criminals, and the Hammers and mages to attack everyone. And the beauty of it is that once they are all dead, you just circle the map (there’s a sort of figure-8 pattern you can do that includes passing through the jeweler’s house) again and it refills with NPCs. A well-placed arrow does wonders for restarting the carnage, and a noisemaker will draw off anyone who gets too close. The bushes near the spot where you took the screenshot are an ideal place to hide and observe.

  7. Dan says:

    Neat idea! Have the gaurds chase you to the jewelers and have them go in on the shake down.
    Kinda like that scene in True Romance. You can just sit back and watch the destructive mayhem unfold and the rank seedy underbelly of the crime world is exposed.

    hmmm….. that might have been too much

  8. rylan whitten says:

    umm i think their all really intresting things but if u kill one of the goons the jewler gos and tells the gaurds

  9. mike harris says:

    the goons are meant to kill the jeweller (if your nice you can save them). but then like 4 city watch dudes with bows and swords are MEANT to come in and start an almighty punch up. by firing the noisemaker outside the goons follow it and have a punch up outside instead, because the watchmen didnt appear due to a problem/glitch the goons that are programmed to be ultra-agressive start killing the citizens instead.

  10. Corwyn says:

    It’s been a long time but this makes me want to play again. Anyone remember how far into the game this is?

  11. Shamus says:

    Not far in. First is the tutorial, then the largish manor. After that you’re in your apartment and can explote south quarter freeform style, which is where you will encounter the above scenario.

  12. Matt` says:

    Played Thief 3 recently, at one point in the game (very near the beginning, I think the first time you go to your house..

    Anyway, a woman with a grudge and her 2 goons are waiting for you, I spotted them in advance and picked off one of the thugs with an arrow (I was expecting the other 2 to bug out a little, search for me, not find me, then when they stopped panicking I’d pick off the other guy)

    Instead the 2nd goon and the woman attacked each other, I can only assume that each of them thought that the other was responsible for the untimely death of the one I killed.

  13. jack says:

    hmmm maybe they were programmed to kill a civilian (the jeweller) and when lured into the street saw millions of jewellers just a thought?

  14. Robel says:

    Ah, the one with lady Elizabeth or something. The most fun thing to do is to go to her hideout which is close, take the money from the table, which is the money she was supposed to pay the goons with, and then watch. The first thug comes in to get paid, they start having an argument, she says that his friend must have taken it, he gets enraged at this and kills her. Well, usually…sometimes she kills him if she gets a chance to strike because she has a poison blade. But usually she just falls really fast. In any way, that was a really sweet twist. But I doubt if you ever save someone`s life, that the AI will act any different than if you had attacked(killed) someone in their presence.

  15. MRC says:

    I played Thief again recently and although I may be a little late with saying this I’m gonna tell you this anyway: I came across the jewelry murder, too. I read your Article and decided to have a little fun with it, so I saved on the spot. What happened is this: Because of some bug (The jeweler heard me bumping something over before the conversation started and after not finding anything he went back to his spot) The conversation didn’t happen. They were just standing there, door wide open, doing nothing. I took my bow and shot out the torches.
    Still nothing.
    Then I walked into them, but all the thugs said was: “Watch out, or I’ll gut you”, the usual stuff.
    Then I got a guard chasing me into the house, where the thugs were. He walked past them. I stabbed one of the thugs, and they bothed pulled his sword. Somehow all the four guards in the area knew where I was and they all ran to the house. I tried to jump up some barrels but it didn’t work and now everyone was stabbing me. My only way out was a Flashbomb.
    With everyone in the room (about 8 people, some idiot civillians included, they probably decided it’s okay to just walk into the guy’s house at night) blinded, I could make a safe way out. I decided to hid in the shadows with my back against the wall. If you do that in pitchdark, no one can see or feel you, So this is the safest way of hiding, just do that when an enemy is about to bumb into you, and you’re safe (only thing is, if he already spotted you, it doesn’t work). When they all started seeing again, they went CRAZY. Everyone was killing each other, and they all died. It kinda went like this”:

    “AA, I’m blinded!” “Ah, I can’t see!” “Who put out the lights?” etc.

    “Oh, I can see again!” “Finally!” “Hey, I’m starting to see again!”
    “There you are!””Taste my sword!” “You taffer!”



    and there I sat, mouth wide open, behind my computer.
    I will see if I can do this again, and then I’ll make a vid. It was crazy.

    PS I get flaws like this all the time in Stonemarket Proper. It’s awesome, because jus one arrow can cause a mayhem in that place.

  16. BigWoodFarmer says:

    Hahaha, I just installed the game again and this happens to me every time! The problem with this mayhem is that you can really not have clean stats after one session of it, tons of bodies found etc.

    I’m sure it’s an AI bug that the thugs just start slaughtering every civilian in sight for no reason at all.

  17. Steve says:

    Question after reading these Thief 3 reviews/your interesting stories makes me wanna try this game. Where do you suppose I could buy it? And for what system?

    I love how it’s an endless chain. They kill new guys spawn they run for guards causing goons to slaugther. Go AI fuckups! :D

    1. Scimitar says:

      You could get it from amazon, or maybe a used game store. I know that there is a computer version and a xbox 360 version, but I’m not sure if it’s on any other systems.

    2. Rosseloh says:

      A late reply, but useful for anyone who doesn’t know already: the game is available on steam, and the steam version is patched up nicely to work with windows 7 (and below).

      And for what it’s worth, Shamus, I had nearly the same thing happen to me, in the same shop. Only, they were only able to get through a few lines of the dialogue before something (not me!) spooked the goons and they went out to commit unchecked violent acts.

  18. Devious Boomer says:

    After stealing the jeweller’s gems and only just realising the gravity of the situation, I decided to help the feller. So as the dialogue began, I ran into the two thugs. This caused them to become distracted and the jeweller took the opportunity and ran the heck away. The funny thing is that the thugs made no effort to chase him down; they were too busy staring at me.

  19. Tudor says:

    I do believe there is a sort of bug somewhere, that wasn’t ironed out.

    For example, I didn’t want to dirty my hands in the catacombs and after the Thief 1 Zombie experience[which was annoying, extremely annoying] I wanted to use my Hammerite allies to take them down. So I lured one zombie into the main hall of Fort Ironwood, the guards started to hit him with a Hammer and the Priest started to also try and hit the zombie too. Only that this Hammer spell deals so much splash damage, and he can’t aim properly, it killed all the guards. Re-load. Lured the zombie again. This time all guards and the priest survived but out of nowhere, one of the guards decided to use his hammer to smack the priest into meeting the Master Builder.

    I also found it funny that if there is someone murdered on the street, everyone, literally everyone assumes it was Garrett who did it. Although the AI clearly saw how a Hammerite and a Pagan splash-damaged a poor person into oblivion, they still assume the thief did it. Same thing for the example above. The guard, after killing the priest was like “wha? Who did this?! Come out and show thyself! ” Damn AI, you just did it!

  20. JudgeDeadd says:

    This reminds me of something that happened the first time I played Thief 3. It was the “St. Edgar’s Eve” mission, where you’re sneaking around a Hammerite church. I stopped by the High Priest’s quarters, but did not sit there too long, instead running off to do things elsewhere. Next time I visited the quarters, I came upon a grisly and amazing sight.

    The High Priest was dead, lying across his doorway, and a Hammerite guard – evidently having only just found the corpse – was standing above him, torch in hand. I could only assume that someone came by while I was away, and wasted the old fella. This theory was only reinforced by a certain letter found in the High Priest’s quarters, which hinted that the old man harbored a disturbing liking for whipping the Hammerite novices sadistically. Evidently a lot of people in the church had very good reason to hate the old guy’s guts.

    “Wow!” I thought. “Even as I was running around other parts of the level, here a scripted murder sequence was taking place. I’m guessing that if I had hung by here in the shadows, I’d have had seen the murder and maybe even had a chance to stop it. How fantastic! How immersive! I wonder if I will need to find the killer later, or if it’s just an excellent bit of flavor.”

    However I quickly found out, funnily enough, that nobody else on the Internet seemed to take note of the enthralling murder mystery written into the level. A more down-to-earth explanation, then, is that the old coot had simply accidentally killed himself with the door, or something—a victim of the natural disaster of video game physics.

  21. Bo says:

    This is it. This is the post that introduced me to Shamus, more than half my life ago.

    I found it via StumbleUpon, of all things, and loved it so much I immediately added this site to my daily reading. DM of the Rings, Free Radical, the longer-form series, the programming…for me, it all started right here, on this post about some AI mooks going haywire.

    I’ve decided to re-read as much of the blog as I can bear to over the coming weeks. I promise not to muddle up the comments with a bunch of waxing nostalgic as I go, but I couldn’t possibly start the re-read without laying a flower on this post specifically.

    Good-bye, Mr. Young, and thank you.

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