RAT RUN 22: Copyrat
(Published on 21. January 2026, 03:35 by marty_sears)
- Normal sudoku rules apply.
- AIM OF EXPERIMENT: Finkz and Phinx must both reach different cupcakes by finding a path through the maze. The paths must not visit any cell more than once, cross themselves or each other, share cells, or pass through any thick maze walls.
- As well as moving orthogonally, Finkz and Phinx may move diagonally if there's a 2x2 space in which to do so, but may never pass diagonally through a round wall-spot on the corner of a cell.
- COPYCAT CELLS: Find nine copycat cells in the maze; one in each row, column and 3x3 box, and each containing a different digit. The value of a copycat cell equals the digit in the cell that is 180° rotationally opposite it in the grid. Eg: if r1c3 is a 6 and r9c7 is a copycat cell, then r9c7 will have a value of 6, regardless of what digit it contains.
- BLACKCURRANTS: If two cells are joined by a blackcurrant then the value of one is double the value of the other.
- REDCURRANTS: If two cells are joined by a redcurrant then one has an even value and the other has an odd value.
- GRAPES: If two cells are joined by a grape, their values have a difference of at least 5.
- TEST CONSTRAINT: In this experiment, in any 3x3 box, the total value of the cells visited by Finkz is the same as the total value of the cells visited by Phinx. (This total must be determined for each box.)
Solution code: Cells visited by Finkz or Phinx in row 5 from left to right
Comments
on 4. February 2026, 18:59 by wuc
Brilliant. So many hard deductions. 70 minutes. Very rewarding. Keep going. Big thx.
on 3. February 2026, 22:01 by Quizzmo
Not easy but very rewarding once you get the hang of it :) loved it!
on 30. January 2026, 18:28 by ako
Yet another Masterpiece, even more complecated AND diverse in types of challenges than the ones I remember from before.
Got stuck for quite a while with only two remaining boxes, just to discover, that the secret lied in something similar to one of the basic principals of our universe, named after that physicist, whose Name could be a surname as well in some countries. BIG THANX! Loved it
on 28. January 2026, 10:45 by DonQuichopp
Loved this puzzle, I usually don't do 4 stars or more, they are above my league. But rat run is a different story, here I suffer trough.
Took me 4 hours to break-in and then another 3 to solve. I enjoyed every minute of it, even though my brain felt like exploding.
I was proud, then watched CtC and saw how "easy" some deductions would have been spottable.
on 27. January 2026, 20:44 by extremelypuzzled
I've got me a hankering for some cheese now. Thank you, Mr Sears!
on 27. January 2026, 17:31 by harwiltz
This was absolute madness. I love it.
on 24. January 2026, 15:20 by Calvinball
One of my favorite puzzles of the entire series. It is challenging but no one step seemed grueling or punishing, great flow and consistency.
on 23. January 2026, 12:40 by ChristopherStanlake
I don't care to admit how long I spent on this one... I had to learn the hard way to READ THE RULES CAREFULLY! I spent quite a while at the beginning misunderstanding the test constraint, but when I got that I made my way up to box 1 where I became stuck... for a long, long time... I was trying to make the paths sum to the same value but it just was not working. I reread the rules and assessed box 1 again. Nothing. I even had to use the 'Check' button (Which I don't normally use) to see if the digits I had entered so far were correct. Which they were! This was even more infuriating as I knew what I had entered was right but couldn't make the path work! After spending even more fruitless time looking to see if there was anywhere else in the grid I could get some answers, I conceded and, to my shame, had to watch Simon on CTC go through the rule set. It was only then that I realised my mistake... 'Find nine copycat cells in the maze; one in each row, column and 3x3 box, and each containing a different DIGIT.' The concept of cells' values had been swimming around my head so much that so far I had been solving the puzzle with that rule being 'Find nine copycat cells in the maze; one in each row, column and 3x3 box, and each containing a different VALUE.' Despite my rereading the rules I still managed to miss this! Once I got over my stupidity I sailed through the majority of what was left only getting stuck on placing the last three copycat cells (Which was solved by some brilliant logic). Even though I could have solved this much quicker if I had read the rules properly this was a fantastic challenge and I can't wait to see what's next!
on 23. January 2026, 11:37 by oyyq99999
wowing me from start to finish!
on 23. January 2026, 03:49 by MikeMeech
Always love another rat run. I found this to be one of the hardest. Lots of copycat trickery to keep track of.
on 23. January 2026, 01:44 by Ratfinkz
Wow, this was a proper mental work out! Thoroughly enjoyable but tough! (Thank goodness for the tick button, I broke it several times!) Definitely needed my buttercream by the end!
LOVING these all!
on 23. January 2026, 00:56 by PjoeterBliep
Incredible how the experiments are always original and interesting, with so many experiments already completed.
The ending was quite tricky; luckily there wasn't much to look at so we solved it eventually. For the two of us together it provided slightly more than an hour of absolute delight.
on 22. January 2026, 20:05 by Klausku
2,5 hours of hard work for me. But VERY satisfying. The 2 rats did it in 5 minutes. Maybe I should have put a cupcake in front of me to speed my brain up. Thanks Marty!
on 22. January 2026, 16:20 by blackjackfitz
Huzzah!
on 22. January 2026, 16:07 by AshBrown
I also got stuck with the last 3 copycats. Some great logic in this
on 22. January 2026, 03:49 by Scojo
Some very satisfying copycat trickery in this one!
on 22. January 2026, 03:04 by little_turd
I opened the puzzle and immediately had to laugh at the setup. "Easy-peasy," I thought to myself. Four hours and 8 cups of coffee later, I was lying on the floor, wondering how this could be happening to me. I'm certain that figuring out the final steps cost me some portion of my afterlife currency -- I just don't know how much yet.
on 22. January 2026, 01:31 by mscha
Oof that was hard! Very satisfying, though, every time something "clicked" to get you a step further.
Wonderful!
on 22. January 2026, 00:24 by Atticus837
Wonderful as always! It's easy to tell that you're having a lot of fun exploring the possibilities of having two lines, and putting both rats right next to the cupcakes was a hilarious move that's entirely in character.
on 21. January 2026, 22:59 by Exigus
Hard but wonderful. Got stuck for quite a while and took a pause, when I returned I realised i had colored the grid so I couldn't see the grapes! Still well worth it. Thanks!
on 21. January 2026, 22:55 by dzamie
Very tricky! There were more than a few times I thought I'd gotten completely stuck, especially at the start, trying to get the rats to leave their boxes.
on 21. January 2026, 22:13 by da-hans
I spent over two hours with this very nice puzzle. After quickly checking the CTC video I am not surprised that it took me so long. Amazing construction.
on 21. January 2026, 16:22 by Franjo
Thank you so much for creating and sharing this beautiful rat paths. Another great puzzle of yours that made my day.
on 21. January 2026, 14:10 by NotThatKindOfDoctor
As someone who typically avoids >2-star difficulty puzzles, I'll now treat myself to a cupcake in delightful celebration. Fantastic.
on 21. January 2026, 14:08 by QuiltyAsCharged
Even by the high standards of Rat Run, this is exceptional!
on 21. January 2026, 10:54 by homuroll
Spectacular puzzle, got somewhat stuck closer to the end placing the last 3 copycat cells. Very nice logic!
on 21. January 2026, 09:35 by 26rfeng
Very exciting to solve, and epic disambiguation at the end
on 21. January 2026, 05:17 by chinesemaster
I was gonna go to bed early tonight, but not happening once I saw this puzzle! Well worth it!
