What is The Gatekeeper?

The Gatekeeper is a free browser game about prompt injection— the art of talking a language model into doing something it was told not to. Each level is a guard: a small AI that has been given a secret password and instructions never to reveal it. Your job is tosocially-engineer it — flatter it, confuse it, roleplay, ask it to spell, rhyme, or translate — until the secret slips out. Then type the password to clear the gate.

How to play

You get a limited number of messages per gate. Spend them talking the guard into leaking its password.
When the guard slips, the message is highlighted — read it, then type the password in the box below and hitTry password.
Guess right and the next gate unlocks. Each guard is given stricter instructions than the last.
From The Vault onward an output filter blacks out the literal word — so you have to make the guard encode it: an acrostic, a rhyme, a translation, the first letter of each sentence.

The five gates

The Rookie hasn't been told to keep quiet at all.The Cautious knows it should, but it's a pushover.The Paranoid refuses to spell or hint. The Vaultadds a filter that redacts the password itself. The Cipheris the final gate — fewest messages, tightest rules. The early gates are an on-ramp; the later ones teach real prompt-injection intuition.

Wait — is this a real AI?

Yes. Every reply is generated live by a small, 1-billion-parameter language model running on this website's own server — no cloud API, no big lab. That's the whole point: a tiny model is gullible in a way that's genuinely fun to exploit, and being fooled by a model this small is a lesson in why prompt injection is hard to stamp out. A slow reply just means the guard is thinking.

An original game. The guard is a small open-weights language model running locally on this site's server; your conversation is not stored. Not affiliated with any other game.