Connect the NumbersFree, no sign-up

Each number appears in exactly two cells. Connect each pair with a path that moves to the neighboring cell up, down, left or right. Paths can't cross each other and a path can't branch. On this page you must also fill the board: the puzzle is solved when every pair is connected and every cell is covered by some path.

Drag from a number with your finger or mouse to extend a path. Drag back over it to erase that part. Touch a cell in the middle of a path to redraw from there, or tap a number to clear its whole path. Crossing another path cuts it at that point. With a keyboard, move with the arrow keys, press Space to pick up a path, extend it with the arrows, and press Space again to let go.

Every cell along a path also shows that path's number in small type, so you can tell the paths apart without relying on color.

Start with numbers near the edges and corners: paths that can only run along the edge, and numbers right next to each other, are settled first. Because every cell must be filled, leaving a corner or dead-end cell empty means no path can reach it. Asking which paths could pass through each empty cell usually shows the next move.

Yes. A program checks every possibility to make sure each puzzle has exactly one solution under the fill-every-cell rule before it's used. The puzzles are made in advance and served in date order.

By the time from when the board appears to finishing the puzzle, fastest first. You only need a nickname, up to 30 submissions per size a day. The finished board is checked against the rules on the server.