Cross off all the symbols and clear the board. The challenge is to form a single continuous chain that visits every symbol once and once only and where each link in the chain connects two symbols that match either by shape or colour. You can leap around the board, but not diagonally.

There are several pre-canned puzzles to try of increasing difficulty. You can also auto-generate new puzzles using any one of the pre-canned puzzles as a 'seed'. Just select your puzzle and hit auto-generate. The resulting puzzle will be the same size and will have a similar distribution of symbols. Auto-generated puzzles are guaranteed to have between one and five solutions, depending on size (smaller puzzles have less) and tend to be a little easier than the pre-canned puzzles. Chain-reaction was inspired in part by Robert Abbott's eyeball mazes which use a similar 'chaining' rule - but where the goal is more specific.

sample puzzle
click button to play


Cross off all the symbols by visiting them one a time ensuring each symbol matches the last either in shape or colour (or both). At each turn you can move horizontally or vertically any distance. The start position is marked with a cross but the finish square could be anywhere!

Use the Puzzle drop-list to select a puzzle.
Use the Restart (Action) or hit space to reset the puzzle.
Use Solve (Action) to sneak a peak at the solution
Use Auto-generate to try a random puzzle (if the auto-generator is still busy - wait a few seconds and try again).

Click on grid to move.

puzzle designs & applet – © Andrea Gilbert 2003-04