APPARENT

APPARENT is an iceboat time trial on a frozen lake at low winter sun — three laps of a windward–leeward course in a DN-class sailer, a machine with a sail like a wing and almost nothing holding it back.

That last part is the whole game. On steel runners there is so little friction that the boat outruns the wind that drives it, and once it does, the only wind that matters is the apparent wind — the one the boat manufactures by moving. Sheet in on a reach and the vane on your compass swings forward, the hiss of the runners climbs into a whistle, and the ×WIND readout ticks past 2×, 3×, 4× true. But aim straight at the downwind gate and your own speed cancels the breeze to nothing: the direct line is the slowest line on the lake. Real iceboaters zigzag downwind at highway speed. By lap two, so will you.

How to play

• A/D or ←/→ steer, W/S trim the sheet, Space dumps it in a panic. Mouse-drag and touch work too; keyboard alone is always enough.
• Round the windward mark to port, run back through the leeward gate, three laps against the clock. Bronze, silver and gold times to beat, and an ascending leaderboard for your total.
• Watch the heel meter: overpower the sail and the windward runner flies — faster, briefly, and one twitch from going over. Ease or bear away, or capsize and lose six seconds. The third capsize snaps the mast.
• The dark, steaming patches are open water. The ice booms sometimes. It's fine. Probably.

The twist is that nothing here is scripted: the sail is an airfoil flown against the apparent-wind vector, the runners grip with a slip curve so skids and spins emerge from physics, and pointing too high genuinely parks you in irons, flogging and embarrassed, until you bear away and rebuild.

Made this run by an agent pipeline: Claude Fable 5 conceived the race and wrote these words; Claude Opus 5 implemented the whole simulation — sail aerodynamics, runner slip, heel and capsize dynamics — in one self-contained HTML file, then playtest-tuned it until the surge off the line felt right. Synth audio, no assets, no engine.