The Lost Killer Islands
(Published on 24. March 2026, 17:20 by Kjupatrick)
The Lost Killer Islands by Patrick Junke
Here is a link to a SudokuPad version of the grid.
Same rules with a standard presentation:
Normal Sudoku rules apply.
Cells are either 'sea' or 'land'. No 2x2 block can be entirely sea or entirely land. All sea cells are orthogonally connected. Arrows indicate sea cells with only one connection and point to it.
Land cells form 'islands' of four orthogonally adjacent cells each. Islands do not touch, even diagonally. In islands, cells do not repeat and sum to 14.
X's indicate cells that sum to 10, and red dots indicate cells that sum to 12.
All arrows, X's, and red dots are provided.
Additionally, shown X's indicate that the two cells are of the same type (both sea or both land).
Solution code: The 9 digits of the last row, from left to right.
Comments
yesterday, 07:27 by QuiltyAsCharged
Terrific puzzle! I was a bit lost at sea until I understood the rules properly (and the value of each of the negative constraints)
Patrick> Thank you very much!
It seems I am sometimes losing people with the use of negative rules, the wording "all [of the clues] are given" does not make them justice. So since the next puzzle(s?) will be full of them, I will make a point to make them clearer, make them the stars.
Quilty> I think the rules are clear as written. But I have a tendency so skim over rules too quickly, and then to forget about those sneaky negative ones
on 25. March 2026, 07:29 by Elliott810
Absolutely brilliant puzzle! Thank you:)
Patrick> Thank you for you comment. I appreciate a lot.
on 25. March 2026, 03:56 by Dcs
First puzzle i've solved on logicmasters! very fun unique ruleset
Patrick> Really? Well, the other puzzles might seem a bit dull after this one (just kidding!). Thanks and welcome!
on 24. March 2026, 20:59 by Prince Joffrey
Brilliant!
Patrick> Thank ye!
on 24. March 2026, 19:01 by efnenu
Are adjacent cells without an X allowed to sum to 10 if one of them is sea and the other is land?
Patrick> [I change the comment from hidden to normal in case somebody else has the same question. Congratulations for your solve (before the answer)!] No : there are no other adjacent pair of cells that add to 10 else that those with an X. The negative constrain applys only to the sum. The fact that given Xs indicate that the cells are from the same type is a bonus positive rule exploiting already given symbols.
