RAT RUN: One Year Earlier
(Published on 6. May 2026, 01:57 by marty_sears)
For the final preliminary 'free-roam' trial, the nine shortlisted rats were placed in a 9x9 space, and their movements were observed and recorded. Each of the digits 1-9 appeared in each row and column.
OBSERVATIONS:
- Every cell in the grid was visited, exactly once.
- No rat's path contained any repeated digits.
- No rat chose to move diagonally at any point.
- Every 2x2 area was visited by at least 2 rats.
- No two rats started on the same digit.
- No two rats ended on the same digit.
- All blackcurrants and redcurrants were eaten.
- No grapes were eaten.
BLACKCURRANTS:
If a blackcurrant sits between two digits, one is double the other.
REDCURRANTS:
If a redcurrant sits between two digits, one is odd and the other is even.
GRAPES:
If a grape sits between two digits, they have a difference of at least 5.
Solution code: Column 3 reading downwards
Comments
on 12. May 2026, 15:26 by davidz32z
Awww I'm a little bummed this is the first rat run I had to watch CtC to solve. Really really good setting and I'll just have to get better at region constructing! Really loved the solve of the irregular sudoku once Simon drew the regions for me!
on 7. May 2026, 18:04 by stranac
I got stuck for a while during the construction because I missed that we're not constructing just any regions - we're constructing rat paths.
After that realization, and another small insight to start the solve, things went very smoothly, even though I usually have quite a bit of trouble with irregular grids.
Thank you for another great puzzle, Marty! I'm always amazed by how much variety rat run has brought us.
on 7. May 2026, 16:35 by mscha
Whew! (I seem to start my comment like this every week, lately, but never so deservedly as this one.)
This one took me forever. For the construction part, I figured out a lot of things, but never quite enough for a real break-in. Only after a day I had a good look at one relatively inconspicuous cell, and that turned out to be the breakthrough. (Same one that got Simon started.) After that, with everything I figured out earlier, the construction part was done in minutes.
Then the irregular sudoku stumped me for a long time. I actually gave up and started watching CtC for a hint, but luckily, I got the right inspiration while Simon was still constructing, so I can still say that I solved it all by myself.
Nice one, but not in my Rat Run Top 25 (which is a very high bar).
on 7. May 2026, 13:41 by woody
Very nice. I love how you have to think about the rukes and rewrite them. I wonder if we will ever have a "normal" rat run again but I can't say I didn't love that one ! Thanks again for this wonderful series.
on 7. May 2026, 08:58 by Puzzlefan
Wow, what a beauty again! One of my favourite Rat Runs. It took me almost 3 hours, but part of that was just enjoying en slowly solving (and no mistakes this time!). Amazing how you thought of this idea, putting in 3 extra regions with 9 rats and the icing on the cake being Finkz's beautiful path. I have to say, I almost felt emotional to see Finkz's name among the others, I really wanted her to do something special (and she did, of course!). Thank you for another beautiful puzzle!
on 7. May 2026, 00:02 by Lykrast
Ok I think I'm 100% outleveled here, but I wanted to see the story for myself before the ctc solve. That was the hardest for me out of all of them I did so far (just finished 23).
Was still a cool concept having the prologue here and having so many rats at once! <3
It took me a total of 2 hours + 3 separates glancing at the CtC solve to unstuck me, with like half that that time for figuring out the paths (and being stuck twice). But I did it!! And now watching the full CtC solve I see that I did a lot of deductions in-between differently so that's nice.
I wanna pet a rat.
on 6. May 2026, 21:34 by DaniK
Lovely puzzle! I had a lot of fun. The moment I suspected what Finkz’s path would be was incredible.
on 6. May 2026, 20:27 by Exigus
I found it quite tricky to get started but then it flowed nicely. Cool addition to the series. Thanks!
on 6. May 2026, 19:44 by Fool on Hill
Really nice puzzle with some cool irregular logic. The first part was not so hard once I got out of my meeting and got my count correct. And then it got pretty tough.
on 6. May 2026, 16:02 by Nairurian
I didn’t expect to get an Origins story to a sudoku puzzle but I’m loving it :D
For difficulty I’d say 2* for finding the paths but 5* for filling in the digits (I’m still not entirely sure if I got lucky with one step or if I just had a flash of inspiration that I couldn’t quite explain).
on 6. May 2026, 15:54 by Dcs
Absolutely beautiful puzzle, I enjoyed the break in to the region building so much.
I kinda hoped the solution code would be one of the rats' runs haha.
on 6. May 2026, 15:53 by Christounet
I must say this one did not feel like a Rat Run puzzle, I was done with the region building in 5 minutes, and I kinda missed the usual surprises of the path-finding and final disambiguations. Anyway, still a great well balanced CC! And very much in line with the storytelling again. Thanks :)
on 6. May 2026, 14:46 by gasp141424
Love Finkz's placement in the centre with no other rats adjacent, she's so fierce.
on 6. May 2026, 11:05 by Rab3aron
Brilliant!
A very smooth solve that flowed beautifully, especially the region building part.
Felt closer to 3 stars for me.
on 6. May 2026, 10:06 by Franjo
Took some time to realize that you used one of my favorite classic constraints for this great episode. Stupid Franjo! Thank you so much for creating and sharing another beautiful puzzle.
on 6. May 2026, 08:57 by QuiltyAsCharged
Amazing how the paths come about with no walls to guide them. I had an easier time drawing the paths than I did resolving all the digits, but I think that's just because irregular sudoku is my kryptonite
on 6. May 2026, 06:55 by Samoth
It took me awhile to figure out the break in, but I enjoyed the flow from that point. A wonderful puzzle, though at this point that should be a surprise to no one.
on 6. May 2026, 05:55 by Silverscree
That felt absolutely brutal to break into but in retrospect it feels quite fair.
I can feel us careering towards a finale and am finding myself unexpectedly, and quite deeply, emotional about it. I look forward to revisiting these puzzles and this story in the future.
on 6. May 2026, 03:46 by Calvinball
Can't help but wonder how science would be different today if Elba had made it. Wonderful puzzle, thanks again Marty!
on 6. May 2026, 03:12 by ViKingPrime
I still can't believe this is the final season. I wonder if there will be a spinoff series? or at the very least a revival series a few decades hence.
