RAT RUN 23: Notable Differences
(Published on 28. January 2026, 02:00 by marty_sears)
- Normal sudoku rules apply.
- AIM OF EXPERIMENT: Finkz and Phinx must both reach the cupcakes by finding a path through the maze. The paths must not visit any cell more than once, cross themselves or each other, or pass through any thick maze walls. The paths may not share cells except where they meet at the cupcake cell.
- 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.
- BLACKCURRANTS: If two digits are joined by a blackcurrant then one is double the other.
- REDCURRANTS: If two digits are joined by a redcurrant then one is even and the other is odd.
- GRAPES: If two digits are joined by a grape then they have a difference of at least 5.
- TEST CONSTRAINT: In this experiment, Finkz and Phinx both visit the same number of cells. Before reaching the cupcake, the Nth digit visited by Finkz and the Nth digit visited by Phinx always have the same difference (to be deduced.) This difference equals the digit on the cupcake cell.
Eg: if the 3rd digit visited by Finkz is 5 and the 3rd digit visited by Phinx is 9, the cupcake cell would contain a 4.
Solution code: Digits in row 5 visited by Finkz or Phinx, from left to right
Comments
on 7. February 2026, 20:00 by apete
An absolute joy. Many thanks for sharing your genius with us.
on 7. February 2026, 09:32 by Ratfinkz
Wow! What a brain bender!! Needed a bit of help there in the middle! Thoroughly beautiful again though!
on 6. February 2026, 13:03 by docpayce
Wow, another great puzzle, Marty, TY very much! :)
on 5. February 2026, 14:55 by MikeMeech
Another masterpiece. I'm amazed at how much work it must be to put all the maze walls and dots in just the right place.
Marty: that is the fun part. The maze format is so flexible and fun to set with because it is so easy to have a lot of control over how restricted or flexible things are just by adding or removing a wall or wall spot
on 5. February 2026, 00:23 by wuc
That was awesome… less hard than the copycat one. Brilliant setting once more. Thx for creating these.
on 3. February 2026, 21:25 by apete
An absolute joy. Many thanks for sharing your genius with us.
on 3. February 2026, 17:36 by virus_dave
Beautiful puzzle. I found this to be VERY hard, possibly the hardest of the entire series for me. OTOH, i get the impression that i was always just missing something, and perhaps more familiarity with the "same difference" ruleset might have made it simpler. Had to restart several times due to an invalid early "deduction", but once I finally identified that early flaw in reasoning, it suddenly became approachable.
Another masterful puzzle by the puzzle master. Thank you for setting!
Marty: Thanks for the comment Dave and glad you enjoyed it and got there in the end. This is actually the 'ziffer' ruleset :) Same difference was in episode 16
Dave: Oops, sorry i used the wrong term for the constraint type. Seeing these makes me actually want to try setting them myself some day, but i'm still having far too much fun solving them ????
on 31. January 2026, 20:31 by ChristopherStanlake
Brilliant! Loved the logic on this one, especially that part of the path that goes from box 5 to 8 to 9. I enjoyed alternating between the top and bottom of the grid. Another great edition to the series!
on 31. January 2026, 17:28 by Klausku
These two rats work together brilliantly. Again, they moved through the maze so much faster than I did. When I arrived at the cupcakes after about 2 hours, there was nothing left for me.
So much beautiful logic in this puzzle. Thanks again, Marty!
on 30. January 2026, 22:31 by DonQuichopp
I felt this one was more approachable than the last one. However I still stared at the same spot for several hours and almost threw away my aim to finish all rat run puzzles without cheating by watching the CtCs videos first.
Then at one point I finally got the deduction that kept me going. Thereafter it was a 1 evening solve for me.
I enjoyed this ruleset a lot! Thank you so much for your wonderful series Marty!!
on 29. January 2026, 16:50 by extremelypuzzled
These are all brilliant, thank you very much!
on 29. January 2026, 08:08 by CorpJigsQuand
There were digits of beauty. And there was the number of the beast(s).
I like it.
on 29. January 2026, 00:39 by monsen
Excellent puzzle, just as the rest of the series. Perfect use of the clues.
on 29. January 2026, 00:22 by VolpeRosso
Another amazing puzzle! And the cute picture brightened my day <3 My brain has been a mess of fog of late, so I kept making silly, oblivious mistakes, confusing the meaning of the dots XD But once I stopped doing that, it flowed beautifully. Thanks again, Marty! Highlight of my week, at the moment!
on 28. January 2026, 23:10 by Elker
What a fun puzzle. Thank you for bringing back Finkz phase three has been worth the wait for sure.
on 28. January 2026, 23:07 by Nairurian
Another banger, this one felt a lot easier than last week (or maybe my brain is just getting back into rat-mode after the break).
on 28. January 2026, 16:25 by mscha
Ziffery!
Again, a wonderful Rat Run puzzle. It got a bit tricky in the midgame, but overall I had less trouble with it than last week.
Very, very nice!
on 28. January 2026, 15:34 by blackjackfitz
Huzzah!
on 28. January 2026, 15:09 by rmulinix
I was stuck on the second part of the initial break.. I couldn't find a clean logic and resorted to some brute force... I'm sure there's a much cleaner solution. After the full breakin, the rest of the puzzle was smooth with some interesting logic. Great puzzle, not my favorite Marty sears puzzle, but that's asking a lot.
on 28. January 2026, 15:07 by Franjo
After more than two hours of solving and enjoying this puzzle I‘m just sitting here with my mouth open. Incredible! Thank you so much for adding this masterpiece to the most popular puzzle series ever.
on 28. January 2026, 12:39 by davidz32z
Obviously incredible, what can even be said? I loved the post text on this one because you can really tell in the paths who is who which just adds a whole new level of clever setting. Truly remarkable, Marty!!
on 28. January 2026, 11:08 by Exigus
One of the best in the series. Thanks!
on 28. January 2026, 09:50 by Christounet
The Big One ?
Now that is some serious teasing here!
Another great episode in the serie. Thankz :)
Marty: hehe it also got mentioned in the notes for episodes 5 and 18
on 28. January 2026, 09:05 by bboom
Still have to get started, just wanted to say I appreciate that you made sure they both get a cupcake in each puzzle
on 28. January 2026, 04:03 by Lyouke
That was an awesome puzzle, definitely one of my favs in the series
on 28. January 2026, 04:01 by Calvinball
marty make puzzle real good
on 28. January 2026, 03:44 by emoney1374
When I sit down and look at a puzzle, I’ll sometimes get the sense of what the puzzle/constructor is asking of me; the type of logic I’ll have to utilize to solve the puzzle. Without fail, whatever my initial assumptions may be, there comes a moment(s) in each and every one of these rat run puzzles where Marty surprises me. A moment of joy where the puzzle starts to reveal its mysteries. A moment I want to hold on to. I look forward to all the moments to come. Thank you Marty
on 28. January 2026, 02:19 by ViKingPrime
You don't need me to tell you what you have in store, you've had 22 other examples so far of inspired, approachable, polished puzzling. You probably won't even see this on your rush in to solve the sudoku before you.
I would though, invite you to take a moment, however brief, to reflect not on the sudoku but on the man. Beyond the hype, beyond the deluge of glazing that is shortly incoming, sits a man with a beautifully simple and pure interest, whose primary concern throughout every single sudoku he has ever made has been the experience of the solver. He cares very deeply for you and that you get to experience his passion the way that he does.
That combination of talent and generosity of spirit is, perhaps not rare, but not common enough that we should fail to acknowledge it when we see it.
