Plank puzzles by SwampBeast
This page offers a challenging selection of plank puzzles generated by a program called SwampBeast. If you think you have plank puzzles sussed then I recommend you try out some of the 10x10s below and see if you still survive.
SwampBeast was written by James Stephens of Atlanta, Georgia, USA. To find out more how this puzzle set was developed read on below or visit www.puzzlebeast.com where you can explore a number of other HTML5 puzzle apps including Kung-Fu, Con-slide and Sliding-block.
Cross the swamp from left to right using the available tree-stumps (fixed) and planks (moveable).
Full introductory rules can be found here.
Click on Restart to restart.
Click on Undo/Redo to replay previous moves.
Click on Replay to restart (with redo active).
Click on the play area to pick up or put down a plank.
Accessible stumps are automatically highlighted for you.
|Staircase||5x5 (3)||29||Target was to reach 5x5 moves|
|Six-squared||6x6 (3)||36||Target was to reach 6x6 moves|
|Expressway||7x7 (3)||50||Just go straight across!|
|Box step||7x7 (3)||48||A curious layout|
|Brute 66||7x8 (3)||66||Named in honour of Route 66|
|Trebuchet V2||9x9 (3)||93||Breach the castle wall|
|Shuttle||9x9 (3)||95||Reminiscent of TCF|
|Pennsylvania Avenue||10x10 (3)||95||Making use of primers|
|Parallel Universe||10x10 (4)||84||An extraordinary multi-layered challenge|
|Special Delivery||10x10 (4)||100||Hit the 100!|
|Junior||8x8 (5)||75||Introducing P5|
|Stack of five||9x9 (5)||109|
|Fort Mudge||10x10 (5)||121|
|Revenge of the
|10x10 (5)||174||Only for the bravest few|
Notes from the Author (2002)
SwampBeast is a Java application which consists of two basic modules, a puzzle generator and a puzzle mutator. The puzzle generator creates a large number of random puzzles, and attempts to solve each one. If a puzzle can be solved, it is assigned a score which reflects (at least in theory) the difficulty of the puzzle.
The puzzle mutator takes the best puzzle from the generator and applies a variety of mutations such as moving planks, adding, deleting or moving stumps, etc. Higher scoring mutations are retained in place of the original puzzle. A typical puzzle on this page is the result of perhaps 100,000 generation steps followed by 10,000 or more mutation steps.
The scoring algorithm continues to evolve from the first versions of SwampBeast. In the early days the scoring criteria were chosen to produce puzzles with long solutions, and as a result many of the puzzles had a large number of "flip-flop" moves, i.e. sequential moves using the same plank. The criteria were subsequently adjusted to explicitly discount flip-flop moves by shorter planks, and as expected the resulting puzzles proved to be harder to solve. The current criteria also give a higher score to solutions that make frequent changes in the set of active planks.
Another twist on SwampBeast puzzles is the use of priming patterns. Rather than starting with a totally random puzzle, the grid is primed with a pattern designed to maximise the use of the longer planks. Pennsylvania Avenue, Special Delivery, and Parallel Universe were produced using priming patterns with diagonal corridors through the puzzle. These patterns were distorted somewhat in the mutation process. (although, surprisingly, the pattern remained completely intact through the mutation steps for Parallel Universe.)
Jimmy Stephens - Feb 2002
puzzle designs - © James W. Stephens 2002
planks applet - © Graham Rogers - 2000-2003
applet hosted with permission from Graham Rogers
applet JS conversion - cheerpj transpiler from Leaning Technologies - 2020