Place nine 3x3 boxes into the grid. Boxes may overlap, but their central cell must not be inside another box. Place a digit from 1-9 in every cell such that each digit appears once in every row, column, and box.
Box boundaries divide the grid into regions. A clue in the corner of a cell indicates the sum of the digits in all cells in its region. A single region may have multiple clues, each of which indicates the same total sum.
A '?' in a clue represents any single digit from 0-9, which may be different for different clues. Leading zeroes are allowed. For example, '?1' may represent 1, 11, 21, etc.
Example
Solution code: Column 1 then row 9
on 10. August 2024, 23:04 by m_or
How I ever managed to solve this sudoku is a mystery to me. This sudoku has been my white whale for quite a while and I am so happy it came together. It seems completely non-sensical when you start and there are a lot of tricky deductions to be made after you've laid the first digits, but at some point, the puzzle opens up and it is a breeze towards the end. Great puzzle!
on 29. July 2024, 06:26 by twobear
Brilliant. Thank you!
on 24. June 2024, 20:20 by applesauce
one of the toughest puzzles I've solved in recent memory, but so worth it! a masterpiece
on 8. May 2024, 00:04 by zzw
Whoa.
That was super hard, but very satisfying to see how everything does in fact resolve at the end. Great puzzle!
on 6. May 2024, 23:56 by Fool on Hill
I have been studying this puzzle since I solved it as I thought I was likely missing things - and I am in awe of how tightly this is clued and also at how cleanly it solves if only you look at the right things in the right order. It is ridiculously clever.
on 2. May 2024, 14:35 by SirJefferE
IcyFruit, you're a madman and this puzzle is insane.
...Keep up the great work!
on 2. May 2024, 13:00 by Fool on Hill
I have added another puzzle to my list of legendary hard solves - quite extraordinary. Glad I found my way through - thanks for setting.
on 26. April 2024, 10:22 by drbs
This puzzle posed a slight challenge, but was rather pleasant nonetheless.
on 26. April 2024, 00:44 by samuel1997
This is brilliant and brutal! If you do want to do this puzzle, I suggest you to spare a whole day for it!