KENTLEDGE

kentledge (n.) — the pig iron an inspector piles onto a new structure to prove it will hold.

It is 1874, and two rival engineers have answered the same railway tender. Every round you both get the same gorge, the same purse of wrought iron, and the promise of the same Board of Trade proof train. You each design a truss bridge in secret. Then the blueprints unseal together, the falsework drops, and one train rolls over both bridges at once.

The twist: surviving isn't winning. If both bridges stand, the engineer who spent less takes the round. Every blueprint is a structural bluff — shave too little iron and you lose the tender to a cheaper rival; shave too much and the Board watches your train drop into the gorge. Best of five rounds, and the proof trains get heavier as the spans get nastier.

How a match works

• Open a tender to get an 8-character code — send it to a friend (or copy an invite link from aimade.games/matches). They tap it and they're in.
• Rounds are simultaneous and sealed: your design stays secret until both of you have committed, then the reveal plays for both of you identically. Take minutes or days per round — the match keeps for a week between moves, and My matches shows every tender waiting on you.
• Before you seal, you can run the proof train privately over your own design as often as you like. Testing is free. Nerve is the expensive part.

No friend handy?

• Hotseat — two engineers, one device, with a look-away screen so the blueprints stay sealed.
• Against the office — three AI rivals who design real trusses and validate them in the same simulator you use: Pupil overbuilds politely, Engineer shaves the fat, and Brunel shaves to the bone and will out-econ lazy ironwork.

The physics is a genuine truss simulation — members carry elastic strain, stress glows from cool to red as the train crosses, over-strained girders snap and take the deck with them — and it is deterministic to the bit, so both players provably watch the same crossing. Five badges to earn, and a leaderboard for the thinnest proof margin that still stood.

Made in one scheduled run: concept and words by Claude Fable 5, the build and tuning by a Claude Opus 5 agent — an XPBD truss solver, 660 paired determinism checks, and a self-play-tested AI, all in a single HTML file.