Plank puzzle collection
Welcome to a new collections page for 2020 dedicated to the world of the plank-puzzle. There is so much swampy ground to cover I've broken up the content here into several new sub-pages. So grab your swamp-boots and start exploring.
The complexity of the challenges may vary, but the goal is the same in all cases; to find a route across a crocodile infested swamp using an inadequate selection of rather short planks. If this is your first visit, I recommend you start on the original planks page.
Original planks: Explore the early evolution of the plank puzzle.
Hex swamps: The vexing hexagonal variation.
Swampbeast puzzles: Really beastly puzzles - enter at your peril.
6x6 grand tour: Searching for new insights on the 6x6 grid.
River-Crossing (2003-2018) and Obstacle Hero (2025)
Plank-puzzles have been available as a hands-on mechanical puzzle since 2003. Bought to market by ThinkFun and distributed globally by Ravensburger. The first four editions (2003-2018) were sold under the brand name River Crossing and included the dog-rescue expansion packs. The most recent edition (2025) is called Obstacle Hero and comes with a cute new theme and a brand new set of 40 hand-designed challenges.
Plank Puzzle - computational complexity
If you find plank-puzzles inexplicably tricky you are not alone. Plank puzzles have been proven 'hard' to solve. For more info see The Complexity of Sliding Block Puzzles (and Plank Puzzles, too) by Bob Hearn.
Acknowledgements
- Jeremy Miller for the HTML5 web-app (2017).
- Bill for the mechanical plank-puzzle.
- Andy Williams for the first successful plank puzzle solver.
- Graham for the original plank puzzle applet and the PPDK (plank puzzle development kit).
- Pascal Wassong for The Centrifugal Force
- Jimmy Stephens (www.puzzlebeast.com) for the SwampBeast puzzles.
- Serhiy Grabarchuk for his technical expertise helped define the River Crossing puzzle set.
© Andrea Gilbert - 2000-2025