One's a Crowd
(Published on 21. February 2026, 07:47 by PhoenixAki)
This is the third puzzle in a new mini-series titled Deja Vu. What does that mean, I wonder...the first person who is able to correctly guess what the series is about will get free access to all of my Patreon-exclusive puzzles for February 2026 (5 puzzles).
NOTICE: This post contains a second link to a challenge mode version of the puzzle. It requires the original break in I designed, which was deemed too complicated to require everyone to find. The normal version allows for a few other approaches you can do instead. I have set the puzzle to 2 stars since that is what my testers felt it was, but I think the challenge mode opening is at least 3 stars if not possibly higher. Please base your rating on the normal version. Very big respect from me if you can solve both versions! To be clear, the challenge mode version is only here to show off the harder and (in my opinion) more interesting opening. There is very little different about the solve path past that point, hence the fog going away at that point.
- Normal sudoku rules apply. Place the digits 1-9 in each row, column, and 3x3 box without repetition.
- Arrows: Digits on an arrow must sum to the digit placed in that arrow's circle. Digits may repeat on an arrow if allowed by other rules.
- All But One: All arrows, except one, contain at least one 1. All 1's, except one, appear on arrows.
- Kropki Pairs: Digits separated by a black dot must have one digit be double the other (a 2:1 ratio). Digits separated by a white dot must be consecutive.
- Killer Cages: Digits in dotted-line cages must sum to the number in the top left corner of the cage. Digits may not repeat within a cage.
Solve on SudokuPad here! (challenge mode)
To increase accessibility to my puzzles, I include hints in my puzzle posts (see below). I also post solution videos on my Patreon and YouTube channel. Puzzles released prior to February 2026, as well as my snackdoku and variant sudoku 101 series will continue to get public solution videos on YouTube, while others will be Patreon-exclusive.
Hint 1: There's 3 approaches you can take to start this puzzle. One is advanced (see the challenge mode hint). The other 2 are a bit easier and involve the 2 parts of the All But One rule. Make sure you are taking that rule into account fully. It requires there to be a row, column, and box that has a 1 which is not on an arrow. Think along those lines and you can start placing 1's, being careful to look for situations where a 1 logically must be on an arrow or can't be on an arrow.
Hint 2: Columns 7-9 are the next area to focus on. Start with box 6's arrow, then look at the 16 cage, the cage has a special relationship with R4C8 and R9C8. Also, the arrow starting in box 3 is more restricted than it may seem. Keep going in this area and you can get 17 digits placed in total in columns 7-9.
Hint 3: Most of the rest of the solve is fairly straightforward, but requires you to be very aware of how restricted each arrow is. You got a taste of that in box 3, now do it for the rest by checking all the options for reaching each possible total. You can place a digit or two and also some pairs from doing this.
Challenge Mode Hint: The All But One rule has 2 statements that when put together are very restrictive. Combined, it means there are eight 1's that must be placed among 5 arrows. Ask yourself how you could accomplish this in terms of 1's per arrow. For example, think about how many arrows could possibly contain two 1's, three 1's, etc. There's effectively only 2 ways to do this and you can whittle it down via some contradictions.
Solution code: Row 8 from left to right (9 digits)
Comments
on 23. February 2026, 08:10 by PhoenixAki
Added a bit more detail to why challenge mode is here now and what it means.
on 22. February 2026, 11:01 by Peteronium
I agree with VitP. Also for me the ‘hard’ version felt (a lot) easier than the ‘easy’ version. Doing the easy first must have helped, but still a notable difference.
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PhoenixAki: That genuinely makes almost no sense to me, to be honest, I'm getting quite confused at the notion that the challenge mode one is somehow easier. I think it has to be bias from doing the other version first. The break-in is absolutely tougher (unless there is a very easy alternative I've missed somehow, can reference the hint I put to compare) and literally the only part of the entire puzzle that is different, besides the fog which is only there for the beginning, is the positions of the box 8 arrow and box 2 white dot. Both of those serve pretty minor roles in the solve overall so there should not be any super notable difference in any part of the solve path other than the break-in.
on 22. February 2026, 08:58 by Mozart40
A beautiful puzzle with a smooth solution. I was amazed at how powerful the "All But One" rule was.
on 21. February 2026, 22:06 by VitP
i'd say the easy version is level 1, except for one hard part in the late middle game, which can be solved by casing the box 8 arrow.
as for the hard version, i found that i can get all the 1s just by studying the arrows. no need to consider the cages. when the last 1 is placed, the fog clears, and the rest solves easily (at level 2), even easier than the "easy" version.
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PhoenixAki: Yes, you only need the arrows for the harder opening, and giving too much other info makes the harder opening able to be avoided, hence putting the fog which is only there to obscure the opening. The rest of the solve past that point is virtually identical so I didn't feel a need to keep the fog going past that point since that version is only here to show off that harder opening. Also, note I did not call either version "easy" like you referred to them as - I stand by feeling both versions are comfortably 2 stars overall due to some of the arrow casing and a few tricky spots (like working out the 8 cage requires you to do).
on 21. February 2026, 17:37 by rojspencer
Really enjoyed this. Liked the unique rule.
on 21. February 2026, 12:10 by sujoyku
Thank you for this lovely puzzle, PhoenixAki! I very much enjoyed the impact of the "All But One" rule.
