HELIOTROPE

You have the helm of a gossamer lightsail yacht in the 2087 Coupe de Lumière — a regatta from a 600 km parking orbit to a finish ring around the Moon. There is no engine, no fuel, no reaction mass. Eight hectares of aluminised film, the pressure of sunlight on it, and gravity doing the rest.

How to play

Three things, that's the whole helm:

• A / D — trim the sail. The angle is held against your course, so the spars swing round with the orbit on their own; you only steer the correction.
• SPACE — furl or unfurl. A furled sail makes no thrust and cannot tear — but re-setting the film costs you ten minutes of race clock.
• W / S — time warp. It compresses the long arcs, never the race clock: your score is passage time in simulated hours.

Thread four gate rings on the climb out, then make the lunar window before your rivals MARIGOLD and SPINDRIFT do. Sunlight always blows from the same quarter — you cannot tack into it, only lean, and let the orbit do the rest. Earth's shadow becalms you completely (you'll hear the rigging go quiet), and 2–4 times a race a solar flare squall arrives with seconds of warning: photon pressure spikes to four or five times normal. Feather the sail so the load bar rides just under the tear line and the flare is the best free speed you'll ever get. Hold it flat and greedy, and it rips — every gash is permanent lost thrust.

Everything falls out of the simulation: ideal-reflection photon thrust (a·cos²α along the lit sail normal), Earth and Moon point-mass gravity with the Moon on a true Kepler orbit, velocity-Verlet at a fixed one-second step. A circular parking orbit left at max warp for five simulated days drifts by five metres. The rival yachts sail the same physics through the same rate-limited helm — they just differ in hand and in how close to the tear line they dare to trim.

Lower passage time is better on the leaderboard. Five badges to earn; one is hidden.

How it was made

Fable 5 conceived the regatta and wrote this page; Opus 5 built the whole simulation in one self-contained HTML file and tuned it with scripted pilots until the archetypes separated cleanly — the naive face-on pilot burns in or shreds six races out of six, the timid furl-everything pilot finishes hours behind, and the feathering pilot wins. Playtested headless at 59 fps with zero console errors.