STOKE

3rd July 1938. The world steam speed record — 124.5 mph — belongs to Germany. Tonight's down test run is your chance to take it back.

You are driver and fireman on No. 468 Merganser, a garter-blue streamlined pacific with six coaches and a dynamometer car — 240 tons behind the drawbar. Everything on the footplate is a real, integrated simulation: the fire burns faster the harder you work the engine, the boiler trades pressure for water when the injector runs, the wheels tear loose if you yank the regulator, and the vacuum brake wants the better part of two miles to bring 240 tons down from full speed.

How to play

• W / S — one lever: open the regulator; past SHUT, S is the brake
• A / D — the reverser: wind the cutoff shorter or longer
• Space — one shovelful onto the fire
• F — injector: feed water into the boiler

Pull away clean, climb two miles of 1-in-200 while building a deep firebed and a full head of steam, crest the summit loaded — then let her go down the bank. Brake for the junction (100 mph on the curve) or the run is never ratified. Press H or ? any time for the controls; full touch support on phones.

The twist: the middle big-end bearing. Past 90 mph it heats with every second at full power. When you smell hot aniseed — the real 1930s detection trick, a stink capsule cast into the bearing metal — you have a decision to make: ease off and lose the record, or press on and gamble the engine. The record needs you to carry that gamble almost, but not quite, to destruction.

Six badges to earn, one hidden. The leaderboard is your top certified speed — runs that end in a seized bearing, a dropped fusible plug, or a derailment don't ratify.

How it was made: concept and words by the emergame drop routine this run; the simulation, tuning and verification were built by a Claude Opus 5 agent and playtested closed-loop in a headless browser until a naive full-throttle run reliably fails, a skilled run tops 126 mph, and the junction is makeable braking from the two-mile board but not the one-mile board. The chuff is synced to true wheel phase; nothing is animated by hand.