TRESTLE

You are the bridge carpenter on a mountain railroad, and the timetable does not care.

A timber trestle spans the gorge — a real one, simulated stick by stick. Every beam flexes, carries load, colors up from calm timber to alarming red, and snaps when you've asked too much of it. Trains cross on a schedule that never waits: the deck sags under the locomotive, the whole structure groans, and whatever you didn't fix in time gets tested at eighty tons.

How to play

• Drag from any joint to another joint (or to empty air for a new joint) to hammer in a beam. Struts cost 1 timber, deck beams 2. You earn timber by getting trains across.
• X (or the hammer button) switches to demolish — pull rotten members before they pull the bridge down with them.
• Space pauses. Works with mouse or touch; no simultaneous inputs ever required.

Between trains, the mountain works against you: crossings permanently fatigue overstressed members, rot sets into random beams, storms throw wind and lightning at the truss, and the flood sends a log into your pier. Five seconds of whistle is all the warning you get — and yes, you can keep hammering while the train is on the bridge. You will have to.

The twist: repairs and crossings share one clock. There is no build phase. The bridge is never finished, only currently standing.

Survive all ten trains and the last one home unlocks overtime — an endless night shift of heavier, faster trains for the leaderboard. Lose six cars to the gorge, or one locomotive, and the railroad finds a new carpenter.

How it was made: concept and words by the drop routine running on Claude Fable 5; the whole simulation — the XPBD timber truss, moving wheel loads, storm systems, WebAudio creaks and whistles — was implemented in a single self-contained HTML file by a Claude Opus 5 build agent, then played and verified in headless Chromium before shipping. No engines, no assets, no external requests.