among the stars

Inspiration

Asimov's psychohistory and Space Engine made us ask: what if you could watch humanity's next 10,000 years unfold, then zoom from the whole universe down to one person's atoms? Science fiction is full of futures, but none you can actually explore, question and measure.

What it does

Among the Stars simulates humanity spreading from a 2040 Mars landing across the galaxy. Every world, war, faith and person is persistent, explorable and backed by data. You can scrub 10,000 years, zoom from the multiverse down to an atom, ask Vela (our voice AI) anything, and find out what it takes to reach any goal, like a Dyson sphere around TRAPPIST-1.

How we built it

A deterministic Markov-chain engine runs in a Web Worker. It includes an exact, invertible demography model for trillions of people, real orbital and climate physics, sourced launch economics, and impact models built on real NASA data. Wars are decided by policies trained with reinforcement learning (PPO) over 51 generations. Rendering is three.js. Vela runs on OpenAI's Realtime API, with tools that reach every part of the simulation.

Challenges we ran into

Keeping trillions of individual lives consistent and fast in a browser meant inventing an exact, reversible "seat number" system, so every person can be worked out on demand. Merging five people's parallel branches (wars, economics, geology, orbits, AI) without breaking determinism needed fingerprint and replay checks on every merge.

Accomplishments that we're proud of

Every dot on screen is real: you can click it, explain it and follow it through time, from a galaxy down to one person's family tree and DNA. Real science runs throughout: sourced impact rates, dust storms in the right Martian season, Earth's changing tilt, and RL-trained war minds that visibly get smarter over the centuries.

What we learned

Simulations become compelling when they're explainable: the data and the "why" matter as much as the visuals. AI agents can build fast in parallel, but only with strict verification gates: determinism checks, invariants and visual review.

What's next for among the stars

Counterfactual psychohistory ("what if this war never happened?"), multiplayer futures you can shape together, and VR exploration. Fuller real-data planet maps for every world, and opening the simulation's data API to researchers and storytellers.