Taking something like the anime Log Horizon as an example, where NPCs (non-player characters) are essentially humans, but in a game (let's wave our hands and say that the tech is available for making NPCs act and react like real humans do).

Presumably, this would not be cheap; each and every NPC would require its own supercomputer, and populating just a small farming village could present quite a struggle. Unless an incredibly large number of people are playing the game, or if the subscription is very, very expensive, such a game would likely lose its publisher a lot of money.

Is there some way I can justify this in my world? The game is actually run by the government? There's cheap life-like AI that somehow doesn't risk the Singularity? The NPCs are all actual people? <-- now that would be quite the twist xD xD

Or... is there some other option?

  • $\begingroup$ You could not presume a supercomputer/NPC, that'll get you a long way in the right direction. $\endgroup$
    – House
    Commented Sep 15, 2017 at 22:02
  • $\begingroup$ Since simulating one second of brain activity took 83K processors 40 minutes, you're talking about serious advancements in memory, multi-threaded multi-core computation, signal speed, and bandwidth. What is the nature of your world? What is its technology level? What tools do we WB:SE folks have to work with? $\endgroup$
    – JBH
    Commented Sep 16, 2017 at 0:19
  • $\begingroup$ You can watch Westworld. The setting is a bit different, but will give you a idea on how human-like NPCs constructed. $\endgroup$ Commented Sep 16, 2017 at 0:23
  • $\begingroup$ Hmmm yeah I was trying to make it real world, around the year 2035. If I'm going for realism, perhaps tech isn't the way to go... Even with Moore's Law, it would be a stretch to implement thousands of AI. Unless Quantum Computing could change that? Though I'm not terribly knowledgeable on that. $\endgroup$ Commented Sep 17, 2017 at 4:17
  • $\begingroup$ You don't need to simulate human conscience ago you have to do is pass turrings test and yout ate good to go $\endgroup$
    – Pliny
    Commented Sep 29, 2017 at 15:43

4 Answers 4


Outsource the NPCs to be controlled by people in poor countries is one option. One person can control a lot of NPCs. This is the idea is kind of like how in a classic tabletop RPG, the DM will play all the NPCs. This does make it a bit hard to coordinate and thus is not easy to hide.

With using AI is that humans are pretty easy to mimic given the constrains of a game, we are probably only a few years away from chat bots that aren't that noticeably different from normal language and the calculations of running them in real time isn't actually that high even today. We can probably run a AI that passes the Turing test in the constraints of a game even today, people in MMORPGs don't actually need to be smart and don't even need to make sense to be honest. I'm sure if you put a bot in WOW that does farming and tie it to cleaverbot, people who have never used cleaverbot wouldn't be able to tell the bot isn't a real player.

Each NPC also does not need an individual AI, 1 AI can easily control all the NPCs. The company would simply need a decent server to handle all the calculations needed. In 10 years or so, hardware advances as well as better trained AI should make these kinds of things pretty trivial.


Advanced Machine Learning

Right now, chat-bots are pretty good at faking a conversation because they've trained themselves to imitate humans. This sort of behavior doesn't require a super computer, rather it needs tons of training data to work with. Put a bunch of players in the MMO for a long time and have them act like NPCs. Then use all that data to train the NPCs to act like them. This won't be perfect, but it will be very close. The downside is these NPCs won't respond well to totally alien circumstances, as they'll have no frame of reference to act on. Still, it's probably the most feasible/affordable solution.



Being able to mimic a human response it's posible rigth now at some degree. Just seeing an animated movie could create an empathic feeling with the drawnings showed in the screen. Using animations George Lucas was able to create an entire race of "spiritual" aliens that alot people end up feeling a deep connection with them.


A game designer probably wouldn't give A.I at each character inside their game. There is alot of quest/misions that would requiere that the player search for some of those NPC's and if they have the free will to roam around that would present alot of issues.

Most NPC would had a basic framework in which they would keep obeying until a user interacts with them. In that moment the A.I would take control of the NPC to enhace the experience and the ilusion that everything it's alive.


The real issue is comunication, since the same question or answer can be said using different words and tones. Computers have a hard time trying to understand what are we saying.

For example:

"Where is the bathroom?"

"Can I use the bathroom?"

"I wanna make pipi!"

Most people would answer to those question with the location of the bathroom. For a machine, this isn't that simple to understand.


There's a massive gap between emulating lifelike and actually being lifelike. You don't need a supercomputer that is able to simulate every individual neuron in the brain in order to have a sufficiently convincing NPC.

AI development in video games is all about superficially simulating human behavior through shortcuts. If you've ever played Oblivion, which was released in 2006, you may have noticed that each individual NPC has a "life". They have a designated home where they sleep during the night. In the morning, they eat breakfast, then leave their home and go to wherever they work. You can actually follow them around all day and watch them do their normal everyday tasks. That's already a lot of detail into making an NPC realistic that most gamers won't even notice, and it was done with 2006 technology.

Of course, that represents scripted behavior. It's a big step in making a believable NPC, but the player doesn't really interact with it. You also need interactivity. Many emotional responses can be simulated with simple triggers. For example, in the VR minigame Star Wars: Trials on Tatooine, if you wave your lightsaber towards R2, he squeals and backs away from you. It feels like a very natural and realistic reaction, though of course it's nothing more than a scripted response that is triggered when the lightsaber is within a certain distance of him.

The trickiest part of natural interaction would be conversation. Speech recognition and conversational AI is one of leading areas of technological development right now. Virtual assistants like Siri and Alexa are striving towards natural language without actually simulating the individual neurons in a brain.

As you pointed out, trying to simulate human behavior at the neurological level is not a cost-effective solution for implementing NPCs. What you would see instead is a complex set of scripted behaviors which do a good job of emulating human behavior without actually simulating a human brain. At the rate that relevant technology is progressing, you can probably expect to have reasonably life-like interactions with NPCs in the next decade.

Lastly, MMOs tend to heavily promote the multiplayer, social aspects of the game. I would think that not being able to tell the difference between an NPC and a real person would creep a lot of players out. If you managed to get the NPCs to perfectly simulate a rational human being, gamers would probably start running around nude while making phallic gestures with their broadswords, chanting lines from Monty Python, just so they could tell each other apart from the AI.


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