What if I told you we’re building virtual people to understand ourselves better?

What would you do if you had control of a world where AI Sims were real enough to live, work, throw parties, and even gossip about their neighbors? A sandbox where you could test your boldest, craziest ideas on a world that doesn’t exist—without the protests, disasters, or Twitter meltdowns.

You could see what happens if you marry that person, have kids, or quit your job to move to Bali. Or go bigger—test universal basic income, slap tariffs on imports, or redesign traffic systems to stop rush hour madness.

No risks. No regrets. Just answers.

That’s exactly what a team from Stanford and Google is building: a crystal ball powered by AI.

When I First Heard About Smallville, I Couldn’t Stop Thinking About The Sims

You know The Sims—that game where you build dream houses, get rich, and start fires on purpose just to see what happens. The researchers started with something like that—a tiny digital village called Smallville.

Where 25 Sims lived human-like lives, complete with work routines, party invites, and unexpected drama. But here’s the twist: these Sims weren’t scripted NPCs. They acted spontaneously, closer to you and me than any game character has ever come.

Then, one year later, the same team scaled up the village. In their latest experiment, they created 1,052 AI agents, each modeled on real people, to simulate society at scale.

These agents didn’t just act—they thought, adapted, and behaved — like us. They remembered conversations, built relationships, and made decisions that rippled through their world in ways no one predicted.

We’ve Always Wanted to Simulate Our World.

Humans have been obsessed with simulations for centuries. Why? Because life is messy, unpredictable, and—dangerous.

If we had tools like Smallville in the past, maybe we could have avoided history’s worst experiments. Imagine Mao testing his China’s Cultural Revolution plans in a sandbox first. Maybe millions wouldn’t have starved.

Or what if David Cameron would have a chance to sandbox the Brexit votes, or maybe Trump could simulate the ripple effects of slapping tariffs on imports?

But let’s be real: If politicians were logical, they’d find a better-paid job w/o taking bribery ;)

What you can expect from this article…

* Smallville: When God Finally Breathed into Adam (the 2023 paper in plain English)

* What if we scale it from 25 to 1000 population? (the 2024 Nov. paper in plain English)

* A crystal ball for the real world

* The big question: Are the AI agents cost-effective, and are we simulated?

Why Is It So Hard To Simulat Humans and Society?

We’re chaotic and unpredictable.

We forget things, change our minds, and sometimes act like complete idiots. You surely know someone binge-watching cat videos instead of doing whatever they are supposed to.

For decades, every attempt at simulating humans fell flat. Early models treated people like chess pieces, following rigid rules. Sure, we have tried to simulate traffic flow or economic patterns or how Covid would likely to spread, we got most of those with a huge error margin.

The Smallville AI agents in these two papers aren’t just reacting; they’re remembering conversations, reflecting on past actions, and acting in ad hoc situations. For example, the AI agent will fix the pipe when you (a naughty God) break it before they step into the bath.

Building this took more than just bigger computers. It took massive breakthroughs in natural language processing (NLP), memory architecture, and behavioral modeling.

Fifty years ago, we didn’t have the tools to build this kind of human-like behavior. Early simulations, like agent-based models from the 1970s, by Joshua Epstein. They couldn’t account for why people choose or how relationships and emotions ripple through a community.

Now, thanks to large language models (like GPT-4), we’re building Sims who don’t just move through the world—they live in it. They form relationships and spread gossip that is deemed messy. It’s dynamic.

And it’s the closest we’ve come to creating virtual people who think and behave like us. It’s not perfect, but it proves we’re finally moving past robotic simulations to something that feels real.

My promise to you: jargon-free, written in plain English, and loaded with graphics. So you get cutting-edge AI research in under 10 minutes.

Smallville: When God Finally Breathed into Adam (the 2023 paper in plain English)

It all began with a tiny virtual town called Smallville. 25 AI Sims lived in houses, worked jobs, and even threw parties.

They weren’t just NPCs on a script. They had memory, reflection, and planning—just like us.

Here’s a question: what makes you “you”?

Is it your personality? Your choices? Or is it the sum of everything you’ve experienced?

In Smallville, the researchers gave AI sim memory—something no NPC in a video game has ever really had.

Their actions feel natural and grounded—like talking to a friend who remembers your last conversation instead of a chatbot parroting back generic answers. It’s a step closer to capturing a human life's messy, dynamic flow.

Behind The Scene.

Think through this with me.

You’re cooking dinner, and you notice the pot of water on the stove is about to boil over. You reach out to lower the heat—observation. While you’re stirring, you think,

Next time, I’ll use a bigger pot so this doesn’t happen again.

That’s reflection. And then you plan:

Tomorrow, I’ll grab a larger pot before starting dinner.

Observing, reflecting, and planning is something we all do instinctively, whether it’s in the kitchen, at work, or even managing our social lives. And it’s exactly how the agents in Smallville operate.

First, they observe the world around them. If Isabella (an agent) sees that her stove is on fire (a playful tweak by the researchers), she doesn’t ignore it. She turns it off.

Next, they reflect. This is where things get a bit philosophical. Agents process their experiences into high-level insights. Klaus (an agent), the academic, might reflect on all the hours he’s spent studying and realize,

I’m passionate about urban research.

It’s a subtle but profound step—turning data into meaning.

Finally, they plan. This is where the magic comes together. Agents map out their day with detailed plans that adapt to new information. When Klaus is interrupted by a friend at the library, he doesn’t just freeze; he recalibrates, finds a new spot, and continues working afterward.

The agents are evolving as time passes. And that’s what makes them feel so eerily human.

Each sim keeps a running log of their experiences, written in natural language. This “memory stream” isn’t just a journal—it’s dynamic. The AI recalls events based on how recent, relevant, or important they are. It’s like how you’d remember your wedding day over what you had for lunch last Tuesday.

John Lin— a Fellow Villager’s Daily Life in Smallville

This is the initial script that John received:

John Lin is a pharmacy shopkeeper at the Willow Market and Pharmacy who loves to help people…; John Lin is living with his wife, Mei Lin, who is a college professor, and son, Eddy Lin, who is a student studying music theory; John Lin loves his family very much; …

John is a small-town charm. Every morning, he wakes up, brushes his teeth, eats breakfast, and catches up with his family.

…

John: That’s good. What are you working on today?

Eddy: I’m working on a new music composition for my class. It’s due this week, so I’m trying to get it finished. But I’m having so much fun with it!

John: That sounds great!

One day, John hears from a neighbor that Sam Moore is running for mayor. This election in Smallville was a seed planted by the researchers.

Sam: Well, I wanted to talk to you about something. I’m actually running for mayor in the upcoming local election.

Tom: Really? That’s great news! Why are you running?

The AI agents themselves came up with what followed— spreading the news, forming opinions, and discussing the candidate. So when John remembers this tidbit and casually brings it up with a friend over lunch:

John: I heard that Sam Moore is running for mayor in the local election. Do you think he has a good chance of winning?

Tom: I do think he has a good chance…

Isabella Rodriguez— a Fellow Villager Planning a Party

Then there’s Isabella, the café owner. The researchers gave her a task: to throw a Valentine’s Day party.

Yes, memory makes these AI Sims feel human. But they don’t simply recall everything they’ve seen; otherwise, it’d be extremely messy. They retrieve memories based on recency, importance, and relevance to the situation.

* Recency: Recent chats, like those she ...

AI Simulation. A Mirror, A Sandbox, A Crystal Ball