click button to start
For each puzzle find the starting square and draw a path moving
horizontally and vertically that passes through each open square
exactly once. At each move the blue runner will always run straight,
as far as possible, stopping only when blocked by the grid's
edge, a black square, or a square already visited.
Use the puzzle drop-list to select a puzzle.
Use mouse clicks for movement (and more... see below)
Use restart (action) or the space key to reset.
Click on grid to mark your start position.
Click on grid to move (or use the cursor keys).
Click on the start-mark to reset current puzzle.
Click on any path corner to unwind to that point.