Tumbler

Two locks, two thieves, sixty codes. Each lock holds three distinct digits of one to five, dealt in secret. On your turn you enter a guess at theirs: the tumbler answers in pins, out loud — gold for a right digit in its slot, dark for a right digit misplaced, nothing for a digit that is not in the code. First guess to turn all three pins gold springs the lock. The deduction is solitary; the clock is shared.

How it feels

• A notebook with teeth
• Pins you can hear across the room
• Sixty codes, one of them yours

What the design is for

• 01

  Public pins, private codes

  The obvious design hides each answer; this one publishes it. Their guesses at YOUR lock teach you nothing about theirs — every pin on their blackboard was forced out of a code you can already read. One blackboard each, both in the open.

• 02

  Sixty codes, no stalling

  Three distinct digits of one to five: sixty possibilities, and every guess rules codes out. The game cannot stall — somebody springs the lock, and a whole night between two notebooks runs 5.1 guesses.

• 03

  The notebook is the whole skill — measurably

  Alone with one lock and no clock, a thief that keeps the notebook springs it in 3.31 guesses and never needs more than five; a thief that ignores its own pins needs 62.44, and has needed 381. That gap is the game. What is NOT the game: choosing cleverly among the codes still standing. Sixty codes and three pins leave about three and a quarter guesses of work even for perfect play, so the notebook is already at the ceiling — `src/games/tumbler/ai.ts` records the refinements that were built to beat it, what each measured and at what sample, and why each was deleted instead of shipped.

• 04

  Two opponents, because two is how many are real

  This title shipped with five. Three of them are gone: one filtered its own past guesses out of a list the pins had already emptied of them — a no-op with a name — and two chose between surviving codes by criteria the probe could not separate from chance. A shelf that offers a rung it cannot beat the rung below is selling a number, and the number was not there.

• 05

  Your lock on your screen

  The view carries your code and both blackboards, and the other code appears nowhere — a board cannot leak what it was never handed. At a shared device the hand-over ritual guards the gap between turns.

• 06

  Taught pin by pin

  Five steps: the entry, the reading of pins, the deduction two answers force — the lesson names the two codes of sixty that survive them, and the test checks that it is exactly two — the fact that their blackboard is noise to you, and then the whole night to pick.