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A game you can hold

A Coin is one HTML file that is a whole game — engine, game and a re-executable proof sealed inside. No install, no server, no link rot. The one below is real: struck from the Sokoban example, 183 KB, playing right here.

Download the coin · 183 KBOpen it raw

Save it, mail it, drop it in a chat — double-click and it plays. The frozen engine inside means it runs identically forever.

Heads

The face

Arms of @janpacan

Title, maker, and the maker's arms — a deterministic heraldic crestdrawn from the handle. This one bears @janpacan:roundel · bark field · green acorn. Same handle, same arms, on every coin.

Tails

The Seal

The proof: replay seed 1, 120 steps, world hash 982dcaec9376e67e. The coin carries a headless copy of its own logic, so anyone can re-run the replay and check the hash — with nothing but the file.

Re-prove it yourself

npx hayao open --assay sokoban.coin.html

Sokoban — assay
  determinism  replay seed 1 · 120 steps
  stamped      982dcaec9376e67e
  re-derived   982dcaec9376e67e

  ✓ SEAL HOLDS — the coin re-proves itself.

The mint is open

Strike your own

One command turns any Hayao game into a coin — yours to keep in a folder, hand to a friend, or post anywhere a file can go.

npx hayao strike my-game/game.ts --maker @you
Read the Coin docBack to the games