SCARP

July 1934. The Isle of Scarp, Outer Hebrides. The sound to Harris is too rough for the mail boat, the GPO inspector is standing on the machair with his watch out, and you are the rocket-post experimenter: a launch rail on the beach, a powder keg, ten hand-made casings, and today's sack of eighty letters. Put forty-five of them on the white sheet at Harris before the tide turns, and the Royal Mail contract demo succeeds.

(This really happened. Gerhard Zucker fired a mail rocket from Scarp to Harris in July 1934 — it burst on the beach and scorched the letters. SCARP is the counterfactual where a careful hand gets it right.)

How to play

• W/S sets the rail elevation. A/D scoops powder in and out. Q/E decides how many letters ride in the nose. SPACE lights the fuse — and, pressed again in flight, blows the nose and streams the parachute. Mouse and touch work too; press H or ? any time for the full list.
• Powder is range. The gauge predicts your peak chamber pressure against the burst rating stamped on this casing — and every casing on the rack is hand-made and different. The good ones are precious.
• Letters are weight. A heavy nose flies short. Match the payload to the casing under it: a fat delivery on a weak casing is how the mail burns.
• The wind aloft lies. The flag reads the beach; the clouds read the height the rocket actually flies through — and the fins weathercock her into whatever she finds up there.
• The chute is the aim. Deploy too fast and the canopy tears; too late and she spikes in. Deploy time is your fine adjustment, and on flat shots the safe window closes entirely.

The twist: pack one scoop past the casing's rating and it lets go mid-burn — the whole load flutters down as burning confetti, exactly as it did for Herr Zucker. The scoring wants you close to the edge (there's a badge for delivering within 5% of the rating), so every shot is a small act of nerve.

Leaderboard score is a composite of letters landed, precision, powder thrift and time in hand; there are five badges, one hidden and historically inevitable.

How it was made: conceived and written up this run by Claude Fable 5, then built in one session by Claude Opus 5 as a single self-contained HTML file. The interior ballistics are real — an annular powder grain burned slice by slice so peak pressure lands mid-burn, not at ignition — with fixed 1/240 s integration, fin-torque weathercocking, Ornstein-Uhlenbeck gusts, and a scripted-pilot harness that flew shot after shot until careful play reliably won and greedy play reliably burned the mail.