Let's Talk About: NPCs

[NewClassic_v1legacy]

The value of something is determined not just by how it appears, but also in what it contains. This is fairly common knowledge, anyone in branding or marketing will be happy to point out that this is why marketing exist for soft drinks and foodstuffs. However, this is something that we don't always consider for games.

Which isn't to say that games have no substance, although that argument could be made for some games, but rather that too often we'll overlook the little details that make up a game's world. We accept palette swaps and sprite-recolors, and we're even more accepting of NPCs being simple stand-ins for substance when they can be so much more. I've said it before [http://www.escapistmagazine.com/forums/read/9.125437-NPC-Stasis-Frozen-in-Time-or-Man-on-a-Mission], and I'll say it again [http://www.haywiremag.com/?p=3988], there's a lot to be said on the topic of NPCs.

NPCs are objects, stand-ins for the crowded streets and well-traveled sidewalks of the world outside. They exist to populate roads with cars, sidewalks with passersby, and taverns with patrons. Each honk of the horn, scream of fear, or simple line of dialog between pulls from a tankard of ale exists to hold a mirror to the world we live in, giving us a shorthand to help us understand the scale of the game.

Open world games reflect this by making NPCs fill the streets and buildings, but don't stand up to any scrutiny. Players who choose to examine the NPCs find they don't do anything, go anywhere, or behave outside of being set pieces. They're a facade, used to illustrate the point without having to build full scripts for each NPC, or radiant AI to give them purpose. They lack the nuance and intricacy of a real city.

On the surface, it may seem odd that NPCs rarely live up to their potential. They could, theoretically, become alike characters themselves. It would be interesting to see a world that functioned independently from the player. A game whose NPCs act on their own volitions, even if the player does not cross their path. Each character going through the day, with their own life to attend to.

NPCs like these could serve to benefit other games, giving an unspoken opportunity for players to explore the world however they'd like, even if it means establishing a home in an unimportant village and following around the villagers to learn their schedules. Or perhaps learning their behaviors to tweak them into doing something so the player doesn?t have to. This could be anything from getting an angry drunk into a barfight in one corner of town to clear the guards out of another, to hiring known thieves to help break into rich villagers' mansions.

Despite how interesting it may sound, programming sufficient artificial intelligence would prove too time-consuming for something that goes largely unobserved. Games that do this to a degree already exist. The Elder Scrolls IV: Oblivion is one such game. NPCs can be known thieves, or shop keeps, or so on. They go about their daily lives, following loose schedules and behaving more or less as one would expect. Thieves will pick pocket locals, sometimes being caught by the guards. At which point they will flee into homes to evade arrest. If caught, they'll be killed, and they will not respawn. That character will be dead, forever, and all of this goes on beyond the notice of players at large.

By and large, though, there's the potential for NPCs to be so much bigger, so much greater, than what they are now. They're capable of so much more substance, so much more depth.

Discussion prompt: Do you think NPCs are employed well, or there should be more examples of radiant AI controlled NPCs? Are there any games that stand out in your mind as good examples of this?

 

[Bad Jim]

Open world games reflect this by making NPCs fill the streets and buildings, but don't stand up to any scrutiny. Players who choose to examine the NPCs find they don't do anything, go anywhere, or behave outside of being set pieces. They're a facade, used to illustrate the point without having to build full scripts for each NPC, or radiant AI to give them purpose. They lack the nuance and intricacy of a real city.

Of course they are a facade. Everything you see is a facade. You'd be surprised how much stuff that logically should be there actually isn't. Radiant AI doesn't make a lot of difference either, NPCs are still stupid. The game will always fall short of showing you a real city because it's just too big a thing to accurately simulate.

It's quite a difficult undertaking to make an AI that acts convincingly human under scrutiny. We would like NPCs that we can have a conversation with, on whatever topic we liked. We would like to be able to share a plan with an ally, and execute it with military precision. These things are a long way off, but they are the sort of things we want from future AI.

 

[Mimic]

I remember being pretty impressed with the NPCs in Red Dead Redemption. I remember seeing a rain storm moving in and seeing people sheltering under buildings. I think the random side quests and greetings from them made it feel like a more immersive living world along with seeing them out hunting, playing games, chopping wood etc.

Good NPCs are like a carefully crafted illusion and its only when they behave unusually that the illusion breaks and they're just dumb computer AIs running into walls etc. I did like it in Oblivion that many characters were individuals with unique names. In future I think it would be good if there were more NPC interaction with each other and the player character in games. I did have a weird moment in Oblivion where I skipped time in Imperial City and guards started attacing each other. I've no idea what happened there.

 

[War Penguin]

I think it really does depend on the game if NPCs are well employed or not. For the most part, they're just part of the environment, like buildings or trees. It would feel strange if they weren't present. Superficial as they may be, they add quite a lot to the world and give a little more depth than if they weren't in the game. For example, you're driving around the city and you see no one out and about on the streets. No cars, no pedestrians, no nothing. That cannot be the best alternative, correct?

Granted giving each and every NPC a certain level of depth would take unnecessary time. For the most part, they're not a major focus of the game, so employing proper interaction with NPCs would just seem a tad silly. Do you really want to know that hotdog vendor's life story before running his stand over with a school bus? No, of course not. Like I said, just part of the environment.

I think The Elder Scrolls games, like Oblivion and Skyrim, did NPCs very well in terms of depth. While the NPCs and the interactions with them are still very shallow, they do serve a bigger purpose to the world than games like Grand Theft Auto or Saints Row. Each NPCs has a name, a job, a path to follow, and maybe even a small bit of personality [small](maybe)[/small]. In sandbox games, none of that matters. They're just there as cannon fodder for the player to crush with a garbage truck or something. In The Elder Scrolls, you can still do that [small](maybe)[/small], OR you can just chat with them, barter from them, maybe do a little quest or so for them, and be on your way. I've started to notice something when it comes to TES games, and that's they don't really populate their worlds with characters. Just people. Not everyone has to have an intricate back story as to how they're a blacksmith in Whiterun. Sometimes a simple blacksmith is just a simple blacksmith. It's up the player's character to form an opinion on that person. And I think that's the best way to have NPCs in a game.

 

[Blood Brain Barrier]

NPCs should always have distinct personalities. If they don't, then don't put them there. This is why I dislike TES, you meet 100 people looking, acting and talking exactly the same way. Takes you right out of the world. I shouldn't have to distinguish between 'disposable' NPCs and useful ones. This frustrated me in Bloodlines. Why can't I strike up a conversation with the guy standing on the corner, but I can with the woman standing next to him? Adventure games, on the other hand, do it right. Every character unique and has a point to being there.

 

[GabeZhul]

The reason why we don't have convincing NPCs (radiant AI or not) is simply because of technical and programming difficulties.

Let's just take a single NPC from an open world game as an example. Let's presume that this NPC (let's name him Joe) is programmed to have a fully developed life-cycle. He gets up in the morning, eats breakfast, goes to work, stays there, goes back home, sleeps.
However this is still very generic and boring. It also doesn't take other periodical things into account, like him having to go to the supermarket to buy food or picking up the kids, or maybe getting home early because he finished sooner with his workload. These things are conditional. Therefore, for Joe to act naturally he has to have a rudimentary system that keeps track of his needs and other extraneous stats.

For example, one process checks the amount of food he has in the fridge, so if it runs low he goes to shop on his way home. However this have to check with his bank account too to see if he can afford it. But then if he is loaded he might decide not to bother with cooking but instead just go to a restaurant. But wait, what if he would have other things he needs money for later? He has to take it into consideration before deciding on what to do.

But then again, he also needs a separate value judgment process. After all, what would his wife Jenny say when she learns that he left the kids in the school until the evening because he focused on his need for food instead? And how will she react to this if this did happen? You have to implement a relationship-system into the game that tracks the variables related to how these NPCs feel about each other. But then if you do it for these two, then what about Joe's best friend Dan? Or his neighbors Arnold and Shelly? You have to put them into the simulation too...

Oh yeah, at this point you are already over just programming behavior, you are building a simulation; and guess what? There is already a game, an entire series in fact, that focuses entirely on NPC interactions and simulation. I hope I don't have to anyone what game series I am talking about (It's the Sims!), and look at how clunky and rudimentary the AI is in those games even though they are specialized in simulating everyday life.

And now comes the part about technological limitations: Imagine that the Sims' rudimentary "life-simulation" is ported into a massive open world game that is normally only filled with your typical backdrop-NPCs. Imagine a thousand, a hundred thousand or even a million sims running around, interacting with each other, both on-screen and off-screen. Imagine all that going on... and then imagine what kind of absolutely brutal processing requirement would that have. And that is just using the very simplistic Sims-simulation. Now try to imagine the same but with actual adaptive VI...

Yeah, we are not going to get there, at least not in the foreseeable future (unless of course if someone starts mass-producing quantum-computers out of the blue)...

 

[lacktheknack]

Their lack of humanity could be better disguised by making a whole bunch more. Seriously.

In Daggerfall, a few key characters did NPC-specific things, but the vast, vast, vast, VAAAAAAAST majority of the NPCs were just spawned in and did nothing but wander around and make the 200-person populated city feel populated - and that's just fine! I much preferred it over the later games having twenty "interesting" people per city with interchangeable guards, because it made even important city locations feel small and quaint.

Ubisoft sandbox games do the same thing, and frankly, I like them more because of it. A few key NPCs are important to the overarching story, and the majority of players (such as myself) aren't really interested in the humanity of the crowds, since they are, in the end, unimportant. They're there for atmosphere more than anything else. All that really matters is the facade of a bustling area.

Sure, it could be interesting to see a game with Turing-test blurring NPCs stretched as far as the eye can see, but the sheer man-power and time needed to make convincing AI would turn it into a huge tech-demo rather than a game (trust the guy who's tried to do AI ;___.

 

[briankoontz]

I love simulations but for whatever reason even the NPCs in the simulation genre are lame. There's a processing issue like Gabe said, but this can be handled by just having a few NPCs - once AI problems get sorted out an amazing game could be made with just 1,000 NPCs or even less, in a village setting for example.

This issue has been talked about for decades and there's clearly a market for games with great NPC AI and more fully simulated NPCs - developers just haven't yet managed it.

I agree with the OPs sentiment that from a design standpoint, it's important that NPCs have dignity, which is tied to their AI quality. This is why right now games like The Walking Dead and The Wolf Among Us are so good - adventure games are the best genre for NPCs. Which is a terrible shame, since there's no AI whatsoever involved.

 

[Smooth Operator]

Well to make them legit you would need to write a unique story for every person with custom AI on top of that, we are talking hundreds if not thousands of characters. All this is not just expensive as hell but the player will only ever see the tiniest fractions, so you are flushing that cash down the toilet while the main story still leaves things to be desired... it's pure insanity.

The other part of the equation is also the player, IRL people do not just come up to you and demand your life story, nor is anyone likely to give it without a strong bond, merely talking to strangers is a very unlikely circumstance, they will also not let you follow them, or go into their house, and under no circumstance would anyone let you search and take their shit.
So if we figure out how to have players themselves act like people who have some social constraint and not poke their nose everywhere we will also eliminate a great deal of that social disconnect, then you also don't need that many interesting people.

At the end of the day it's all movie magic, the props also don't look so great up close so a smart dev will only let the player zoom into to the extent where they look good.

 

[StoleitfromKilgore]

@Charcharo:

Agreed. Correct me if I'm wrong, but from what I know, there is still no game that made such an effort at making the maps come alive. A few examples:

- When mutants in "Smart Terrains" were killed off, they did usually respawn in the areas between the maps, which were inaccesible for the player. They then had to actually wander back to their assigned "Smart Terrain" across one or more maps. Plenty of opportunities for interesting encounters.

- They have to eat and they do. "Flesh"-mutants are the most cowardly of the mutants in "Shadow of Chernobyl" (first of the three Stalker-games), but sometimes they attack. I assume that it is because of low "satiety". Once I watched a pseudo-dog drag the dead body of my protagonist (game-over screen) for 100-200 meters, till it arrived under a tree and started eating me. ;-)

- Very varied behaviour of mutants. Fleshes are cowards, dogs are not much better, but are usually fast and numerous and employ pack tactics, snorks are good at hiding etc. etc.

- NPCs move within maps and sometimes between maps. Usually this is triggered, when the player advances the main quest line. New stalkers arrive, "smart terrains" which were needed for the main story get refilled with a new set of mutants etc.

- No matter who it is, unless you are in one of the "no-gun-zones" everybody can die.

I'm sure there are more points in the favor of Stalkers "A-Life"-sytem, but that's all I can think for, for the moment.

 

[MysticSlayer]

It's sort of hard to simulate both advanced AI for every NPC and make the place feel like it has a decent-sized population. More often than not, games for a smaller number of relatively well-characterized NPCs (e.g. The Elder Scrolls, Fallout) or they go for having more NPCs but giving only few of them any real personality (e.g. The Witcher, Grand Theft Auto). And it isn't just about time or money. Can you honestly imagine a game with all the NPCs of recent Grand Theft Auto games living their own lives? Could even the most advanced gaming PC be able to handle it, especially with the graphical fidelity we currently have? Furthermore, even if we can simulate all of that, how much more negatively will the inevitable bugs affect our illusion? At least in my case, when games try too hard for immersion and making the world feel real, every little mistake can completely break the immersion potentially for hours.

Overall, I think it is nice to think about but just unrealistic with our current time, budgets, and technology. For now, though, I am reasonably content with the two alternatives we're given so long as each is done well.

 

[GamerAddict7796]

GTA V and Red Dead Redemption had amazing NPCs. I loved walking through MacFarlane's Ranch at night and seeing ranchers huddled around the fire talking about local events. It was a game where I chose to walk through the towns instead of sprint everywhere so I could catch some of the dialogue.

In GTA V you see farmers farming, shoppers shopping and people stood around nattering. If you follow someone who's on the phone there conversations make sense. When I'm not going on a murderous rampage, I feel bad if I disrupt them and they run screaming because I become so immersed I just stroll around looking at the NPCs around me.

While typing this I just thought of Saints Row 2 which has some of the best AI behaviour in any game ever. Walk through the university and you'll see students doing homework, petitioning and cheerleaders doing human pyramids while singing. It's a shame that the game encourages you to just fire bazookas at everything because if you stop you'll notice a very alive world.

 

[SmugFrog]

You guys have some great points about the background NPCs. There's no way we have the processing power to do it properly, for everyone to be written out with their own story and choices. I like how Skyrim/Oblivion has people going about their lives (mostly), even if it's not a complete system they're inhibited because of gameplay choices. Early tests of Oblivion there were writeups about how people would steal important or quest items, kill each other, things like that. It wasn't possible to let them be free and still let the player play the game without bugs/glitches/broken quests; hence why the "essential npc" thing, where they can't be killed. I've added in a mod that adds adventurers and other random NPCs - and even though they don't have their own storyline, you can converse with them, and see them out fighting and doing their own thing, or camping at night. It just adds to the atmosphere. Can you imagine the Assassin's Creed cities without all of those NPCs?

In relation to AI, I'd like to show you this little graphic I created. Something I hate about FPS games is when the enemy always knows right where you are, no matter how many walls are between you. I had this shoot-out with an Elite while playing the original Halo on the Xbox One... original xbox:

This blew me away. While it doesn't seem like a big deal now, 13 years ago most games didn't do this type of thing. Meanwhile, when Half-Life 2 was released in 2004 (and even though I love that game and series) I felt like the AI didn't perform up to the standards of a game released 3 years prior. There's no sneaking up on the combine - they know where you are as soon as you poke out of cover.

I think what limits development of AI to the point of everyone having more story/life is that more programming would be required (which, I think TES is doing a good job of figuring out how to do that) and also voice actors and conversations. You can record many generic sentences, but in the end, with a lot of time in that gameworld you're going to start hearing the same things (and also seeing the same faces and clothes, depending on how in depth those systems are).

I believe MMOs were, when they first emerged, expected to be a way to remedy these limitations. With several thousands of people playing together, it could be like that realistic world where everyone has their story and does their routine. The problem is that real world people don't want to roleplay the people with boring day to day lives; we play for the fun and the adventure.

20 years ago NPCs stood around and waited for you to interact with them. Who knows where we'll be 20 years from now?

 

[StoleitfromKilgore]

I think we also need to be careful what we are asking of developers. I have played "STALKER-Call of Pripyat" and some mods like "Old Good Stalker Evolution" and "Oblivion Lost", which try to have a lot of movement on the maps. In CoP, I didn't really like the results. There were far too many meaningless battles going on in which loads of mutants/stalkers got killed off, only there often was no real reason to care about it. I usually hadn't encountered them before and thus didn't care about their deaths. The same applies to most of the non-permanent-camps. Since blow-outs are occuring quite frequently, NPCs don't stay in one place for very long. Thus there are barely any locations where you will meet the same people more than once. It was similar with "STALKER-Clear Sky" and its faction wars. Just like in CoP and OGSE there are far too many people dying all the time. But there are other issues, which will make it harder to actually relate to NPCs and make the world more believable. "STALKER-Shadow of Chernobyl" has comparatively moderated and well crafted A-Life.

I honestly believe, that more movement and generally more stuff happening is not something we should be demanding from AI-systems. Or at the very least I'm cautious about this approach since I have not really seen it done well so far. As I have already mentioned, part of why A-Life worked in SoC was, that AI usually had something specific in mind, like for example getting something to eat, or getting back to its "Smart Terrain". With CoP it often just seemed like two groups were meeting up at an intersection of their paths to murder each other off. I have not played CoP enough to judge it with reasonable certitude at this point, but I felt, that the more static approach of locations which served some function in terms of lore or gameplay, with movement being clearly tied to some specific goals, was more believable than to always have a lot of movement and general chaos. They are in the zone to search for artifacts, right? Not to murder each other in the most senseless ways possible. At least "Clear Sky" had the excuse that a severe blowout had messed up the zone and given access to a lot of unexploited areas, which had sparked a faction war.

The point about "senselessly murdering each other" also reminds me: Wouldn't it be cool, if the AI knew how to actually retreat? I know, in STALKER some of the animal AI already runs away under certain circumstances, but the human AI still tries to carry through all battles, no matter the costs. Not exactly believable. Shouldn't it be more along the lines of a lot of shooting and not much hitting? I mean, who wants to die. In general, toning down the FPS-aspect of the STALKER-games could have helped making it more of a survival-experience, since ressources would not have been quite as easily available. Of course, this would have had to go along with other balance-changes, like the maps (especially SoC) not being littered with tons of easily accessible artifacts (which brought in a lot of money). Also, instead of bandits being outright hostile or not hostile at all (SoC and CoP respectively), it would be better if they were capable of adapting to the player and thus behaving in a more graduated manner: Demanding a toll, forcing you to stay outside their territory, some assassination attempts, chance of getting aggressive, when witnessing, that the player has picked up an artifact etc. etc.

Some of this was in the game and I feel the reputation-system from Far Cry 2 was also a good step into the right direction. It definitely did influence their behaviour in cease-fire zones and maybe also in combat, but in any case, they talked differently depending on reputation of the player, no matter if in the zones or in combat. Unfortunately it never seems to influence, if they want to shoot you or not. Reputation could have been utilized in great ways. For example, the militia could demand a toll, but they wouldn't do so, if your reputation was high, they might try to rob you no matter which side you are on, but they might be to scared, if your reputation was high. And so on, and so on.

I guess it has turned into somewhat of a rant. Hopefully it's still somewhat readable ;-)

 

[SmugFrog]

The point about "senselessly murdering each other" also reminds me: Wouldn't it be cool, if the AI knew how to actually retreat?

That would be great, as it's pretty unbelievable in some games like CoD where waves after waves of drones run at you to just get mowed down. CoD has done a great job of making you retreat in a few games, where you're being overwhelmed by more soldiers than you can deal with, but I don't think I've really seen an enemy retreat mechanic performed well in a game. I'm sure there was one, but the rest of the game was probably unimpressive so it doesn't stick out in my mind. I think it would be more important if they didn't have infinite ammo as well. They enemy AI seems to have the mentality in a lot of games to "kill you or die trying."

I really like how in Skyrim some of your opponents will surrender. That was negated by the fact that

1) Your follower will keep attacking them and kill them anyway and
2) Your opponent will surrender for maybe 10 seconds before coming back at you again.

I've tried to find a good mod that lets your enemies surrender, but the one that looked interesting made too many other gameplay changes for me to try it (or maybe it had comments about bugs and crashes, I can't remember).

 

[StoleitfromKilgore]

I just thought of a few examples:

RAGE:
The humans actually did retreat. This was just a delay though. No true retreat, since they could just pull back within the same level. Basically they just took new positions.

STALKER:
As far as I'm aware they only panic and run away, if they have no weapon. The wounded enemies have to either be killed or left to bleed out. NPCs even walk up to them and finish them off at close range.

Far Cry 2:
I don't think, that they ever actually run away, but they sometimes talk about it, if the reputation of the player is high enough. The might behave more cautiously under such circumstances, but I'm not sure.
Also, I once encountered a lone guy guarding a boat, somewhere in the middle of nowhere. I snuck up to him and when he noticed me, I was already aiming at him through the ironsights. I was quite surprised when he threw up his arms. When I was not aiming at him anymore however, he just tried to shoot me.