The engine, outside the game
The life simulation behind 1in8B is versioned, seeded and reproducible: same seed, same model, same life. This page documents what exists today — the model hash, the shipped engine bundle and the small read-only feed — and what does not.
What the engine is
A person is born in one of 172 countries and territories at public birth shares and lives one life, year by year, against public life tables and country statistics. It is fiction told at the odds of the open data — never a forecast, never a record of any real person. The build spec, the data sources and the honesty boundaries live on https://in8b.com/methods/.
Same seed, same life
Every life is driven by its seed and the model version. Run the same seed on the same model and you get the same life, every time. A replay battery re-runs seeded lives on every build, so the claim stays measured rather than promised. The model driving this site today is engine-2026-0c775f958a5154a8 — when the model changes, the hash changes with it.
Run the engine yourself
The exact headless bundle the classroom lab runs ships with the site at https://in8b.com/classroom-worker.js — no install, no key, no account. Load it as a web worker and ask for five sample lives born somewhere today, one country across 1950, 1975, 2000, 2025 and 2050, or a random world sample of a few hundred lives. Each life returns country, birth year, sex, lifespan, education, children, work and cause of death, and the model hash that produced it.
The decision policy, disclosed
Inside the lab the engine answers its own decision points with a fixed policy: one valid choice drawn uniformly, default game focus. The policy is declared in the bundle as CLASSROOM_MODEL, next to the hash. Work that needs another policy must say so — the bundle ships no hidden decks.
The public read-only feed
Two small read-only endpoints serve the public, pseudonymous side of 1in8B: the shared notes feed at https://in8b.com/api/posts and shareable life links at https://in8b.com/s/<key>. Fields, paging and the one-request-a-second habit are documented on the Developer API page.
What we do not offer
No hosted per-request life service, no keys, no paid tiers — the engine already runs where it runs: in your browser and in the classroom lab. And no predictions: the model answers how lives go at public odds, not what happens to any real person, market or policy. If a number matters, measure it on the data, not on this fiction.
Citing the engine
Credit “1in8B (in8b.com), model engine-2026-0c775f958a5154a8” and link https://in8b.com/methods/ for the spec. Teaching or research with the lab? Write to [email protected] — the classroom door stays open.