Solo Grid
0:00Options are locked into each board and its share link. Changes apply to the next board you build.
Tap a cell to cycle: empty → X (ruled out) → token → empty. Swipe across the board to X out every empty cell you pass over; start a swipe on an X to erase X marks instead. Swipes never move tokens. Arrow keys move, Space cycles.
Share this board
Groups
Rules
- The board is a square grid, 8 × 8.
- One token in every column.
- One token in every row.
- No token touches another, side to side or corner to corner.
- Each token owns one group, marked by a color and an icon.
- Every cell belongs to a group.
- The groups allow exactly one valid placement.
How each board is made
The generator first places the tokens: a random layout with one per row and column and none touching. Each token then seeds a group, and the groups grow one cell at a time until they cover the grid.
A solver then counts every valid placement for those groups. While a rival placement exists, the generator finds a cell where the rival puts a token and the intended layout does not, and hands that cell to a neighbouring group. That leaves the rival with two tokens in one group, so it fails, while the intended layout still works. It repeats until the solver finds exactly one placement, then runs a final independent check before showing the board.