Recoil: An Introduction
(Published on 17. March 2025, 18:09 by damasosos92)
Some rulesets, no matter how brilliant, often go unnoticed. In occasion of the Turn 5 of The Skunkworks League I decided it's time to shining a light on one such hidden gem: Recoil. This ruleset was introduced at the end of 2020, and until now, it only had a single published puzzle, created by a LMD user named SebastianSimon and still unrated. You can find that puzzle at this link. The name Recoil was suggested by the user Thomster and I decided to take it.
This pair of puzzles is my first introduction to the genre. You will find other two harder puzzles with IDs 000MDU and 000ME7.
Rules
Starting at the black diamond, draw a directed path through the centers of some cells in the grid. Path segments are drawn sequentially from cell to cell, such that the first path segment is drawn from the black diamond to an adjacent empty cell, the second segment is drawn from that cell to the next empty cell, and so on until the final segment is drawn and the path ends.
The path cannot branch or revisit a cell it has visited before.
Every time the path enters a new cell, a “recoiled cell” is placed in the first empty cell in the opposite direction. This recoiled cell may skip over gaps in the grid, other recoiled cells, or other path cells.
The path cannot enter a cell if its corresponding recoiled cell cannot be placed into the grid.
All cells of the grid must be visited by the path or contain a recoiled cell.
In the example below a simple Recoil puzzle is shown. All the recoiled cells are in grey. Please notice how the recoiled cells work for the last two steps of the path: r2c1 is the last recoiled cell of the entire puzzle because it's the nearest empty cell in the opposite direction of the last step.
SebastianSimon's puzzle also includes an animated GIF of a simple solved Recoil, which may help you better understand the solving process.
Special thanks to X_Sheep, for implementing a functional Recoil editor and player on Pzprxs, and to Nordy, for the invaluable help in writing the ruleset.
Have fun solving and please leave a comment after your solve!
Solution code: The number of path cells in the last two columns of Puzzle 1, followed by the number of path cells in the last two columns of Puzzle 2 (4 digits).
Comments
on 2. July 2025, 18:06 by Fra314
Very cool now that I have the knowledge to at least attempt these :D
on 19. March 2025, 23:26 by Thomster
Feeling deeply honoured, my suggestion was chosen :)
To be honest, I couldn't even remember solving the puzzle nor the suggestion...
on 19. March 2025, 05:59 by Nordy
Absolute mind bender. Loved it
on 17. March 2025, 23:25 by Lizzy01
I remember seeing that puzzle back then. I think it's a very interesting ruleset, but it does not really agree with my brain for some reason. By far not as badly as with u-bahn though, I can't even solve the easiest ones of those usually. These ones are about 2.5 stars for difficulty for me. Very nice nonetheless!
on 17. March 2025, 22:14 by wuc
Refreshing new ruleset. I tended to try out instead of use logic in puzzle 1. In the second I tried only to use logic. Great fun thx.
