Board. Five dials of twelve sockets around a hub, read like a clock with 12 at the top. A dial can be turned one click, carrying its marbles, pins and Keepers with it.

Pieces. Each player holds the twelve pentominoes and one pin; every piece is played once. Light moves first. A piece goes on empty sockets in any rotation or mirror and may run past 12 onto 1. With gravity, it must be settled: pushed one dial toward the hub, it would be blocked. The pin ignores gravity. If a piece fits, you must place; pass only when nothing fits.

Ticks. Three per player per game, one per turn, before your placement, before or after your Keeper moves. A tick never fills a dial.

The Keeper. Once a turn, before your placement, before or after your tick, it steps one socket: along its dial, straight inward or outward, or between the hub and any dial‑1 socket. It may swap with one of your own marbles beside it, along its dial, inward or outward (never from the hub); a Keeper boxed in on every side by the other side's marbles is locked down until a tick or a strike frees it, and one hemmed into a few sockets with no way back to the hub is partly trapped. If its step fills a dial's last socket, the dial waits and strikes when you place or pass, with you as the striker. Nothing strikes in the middle of a turn.

A locked board. When both sides pass in a row with pieces still in hand, the fullest dial strikes by itself, and every dial tied with it for fullest strikes too: each side scores its own marbles there, nobody scores the chime, and a Keeper on a struck dial goes home without a ride. Then play goes on, as often as it takes.

End. When both hands are empty. A turn without a placement is a pass, whatever the Keeper or a tick did first. Only after twenty locked boards in one game would two passes end it, each piece left in a hand giving the other side one point; no game has come near. Most points wins; equal scores draw.

A match is the best of 3 or of 5 games against one opponent — Play a Match on the home page makes a code to send. Colours alternate; a win is a point and a draw half; the first past half the games wins, and a tie after the scheduled games is played off one game at a time.

Each player has spins of the board for the whole match: one in a best of 3, two in a best of 5, carried between games. A spin comes at the start of your turn in place of the tick: every dial turns by its own random amount, the marbles keeping their order.

In a match each player's Keeper is drawn in the colour they chose on their profile, on both boards: one from the light set for the games they play as Light, one from the dark set for the games as Dark.

Game rules & setup holds variants kept for testing: the flat chime, other ride scales, the unsettled ride, swaps with any marble or only inward and outward (the 1.0 rule), two passes ending the game (the rule until 1.3), other prices for a stranded piece (five was the 1.0 and 1.1 rule), a strike as soon as the Keeper fills a dial, several ticks a turn, a bonus placement after a strike, a returning pin, tick refills, and the tetromino army. Changing any of them starts a new game; the standard rules are the defaults.

Choose your side and the bot's level in Game rules & setup: Beginner plays any of its ten best placements, Novice its best few, Club reads your best reply, Expert searches three turns ahead, Master searches wider and deeper and takes up to ten seconds a move. Your local rating (from 1200) moves after every game against a bot unless you took back a played piece, used a hint or loaded a record; taking back a Keeper move or a tick before you place does not count. Practice games are unrated.

The round buttons beside the board step back and forward through the game without changing it; hold one to jump to the start or back to the live game (the arrow keys, Home and End do the same). Undo takes a move back for real: a Keeper move or a tick, freely, until you place (online too); a piece already played only in a game against a bot or pass & play.

Puzzles put a position from a real game on the board with one clearly best turn (Trap the Keeper puzzles: a trap to find, made without giving anything away). Hint asks the Expert engine for its turn and previews it (the game is then unrated). After a game, Analyse scores each of your turns against the engine's best and marks the record: ?! a slip, ? a mistake, ?? a blunder.

Game record… in the menu writes the game out turn by turn; paste one back to replay it or play on. 7. L K>1:3 T2- Y.5@2:4 !2r {L 21 · D 9} — turn 7, Light: Keeper to dial 1 at 3 o'clock, dial 2 back one click, the Y on dial 2 at 4 o'clock, dial 2 strikes with a ride; the score is then Light 21, Dark 9. A line is always in the order of play: Keeper, tick, placement.

• L Light, D Dark. Dials are numbered 1–5 from the hub outward; a socket is dial:hour, 12 at the top.
• K>2:9 the Keeper steps to dial 2, 9 o'clock; K~2:9 it swaps with your marble there; K>hub it goes home.
• T3+ dial 3 turns one click clockwise; T3- counter-clockwise. S3.7.0.11.5 the board was spun (match play): dials 1–5 turned by those clicks.
• Y.5@2:4 the Y piece, orientation 5, its first cell on dial 2 at 4 o'clock and the rest reaching outward. The pieces: pin, I, L, Y, N, P, T, U, V, Z, W, F, X; the pin is just pin@4:5. The same placement may be written cell by cell: L{1:12,2:12,3:12,4:12,4:1}.
• pass nothing fit. Two in a row with pieces in hand: the fullest dial strikes by itself, noted {lockdown: dial 3 strikes, L +5 D +6}. again a bonus placement in that variant.
• !2 dial 2 struck; !2!4 two dials at once. Suffixes: r the striker's Keeper rode it home, e the Keeper came home without a ride (it arrived this turn), x the other Keeper was captured, s the other Keeper was shaken home under grace.
• {…} a comment: the score after a strike, a chime, a stranded tally (D strands 2, L +2), the result. A ; starts a remark to the end of the line. After an analysis, ?! ? ?? mark a slip, a mistake and a blunder beside the turn.
• The headers at the top name the game type, the ruleset, the players, the date and the result (L 66–52, D 20–31, draw, or * for a game still on); Settings lists only what differs from the standard rules.

• Tap a piece in your hand, then tap a socket: the piece's innermost cell lands there and the rest of it reaches outward. Drag the preview to adjust. Press Place beside the piece in your tray (or tap the preview again, or the hub) to place; ✕ puts it back.
• Hands are laid out from simplest to most awkward, left to right: pin, I, L, Y, N, P, T, U, V, Z, W, F, X. A played piece stays in its place as an outline.
• The numerals turn the piece: 9 rotates left, 3 rotates right, 12 mirrors inward/outward, 6 mirrors left/right.
• Press and hold any socket, then swipe along the dial to turn it. That spends a tick.
• Tap your Keeper (on the hub, or on the board) to lift it; the sockets it can reach light up. Tap one to step. K does the same.
• Keyboard: R / Shift R rotate, F / Shift F mirror, Enter place, 1–5 then ← → tick a dial, U undo, H hint, P pass, Esc deselect.