Ledger Lock

A six by six grid of digits with a sum target printed on every row and every column. You switch cells on until each line hits its target exactly, and the second clamp is that two active cells may never touch up, down, left or right. A readout under the board reports how many rows and columns currently match. The board is reached through the playtrike hub's daily slot, numbered and dated in the header next to a streak count and a clock.

1. Read the two rules printed beside the board: hit every row and column target exactly, and keep active cells from touching up, down, left or right.
2. Tap a cell to toggle it on or off.
3. Check the rows matched and columns matched readout under the grid to see how far the current arrangement sits from the targets.
4. Press Clear board, or the R key, to wipe the grid and rebuild the arrangement.

Ledger Lock is arithmetic and adjacency pulling against each other. A cell you light up serves a row sum and a column sum at the same time while banning its four neighbours, so the good moment is the toggle that settles both of its lines at once. Six by six is small enough to hold in your head, and there is no score to chase beyond the clock, the streak and getting all twelve lines matched.

The only running score is the line under the board, rows matched and columns matched out of six each. The header carries the puzzle number, the date, a streak count and a clock. The rules insist on exact sums, so a line that overshoots its target reads no better than one left empty.

Daily

One board per day, numbered and dated, with a streak counter beside it and a hub link back to the rest of the site.

• Every cell you switch on quietly forbids its four orthogonal neighbours, so chase the knock on blocks before you chase the sums.
• R clears the whole board in one keypress, which makes it cheap to abandon a branch you have stopped believing in.
• Each active cell serves a row target and a column target at once. Look for the cell that closes two lines rather than the one that closes the loudest.