Classic sudoku asks “what goes here?” Rescue asks a different question: which of these numbers is lying?
How it works
A Rescue board is a real sudoku that somebody else has already started, and made a mess of. Most of the empty cells have been filled in, but some of those entries are wrong. Your job is to find the mistakes, fix them, and finish the grid.
There’s one thing you can always trust: the original clues are never wrong. They alone still determine the one correct solution, no matter how much noise has been written on top.
Loud and quiet mistakes
Some wrong numbers give themselves away: a second 6 in a row, or two 3s in a box. Those are loud mistakes, and you can spot them by scanning.
Others are quiet. The wrong digit doesn’t repeat anything; it just isn’t the digit that belongs there. The only way to catch a quiet mistake is to reason from the clues and notice that the cell can’t actually hold what’s written in it.
Higher levels lean towards quiet mistakes, which is what makes them harder.
How to rescue a board
- Trust only the clues. Treat every other number as a suggestion until you’ve proved it.
- Clear the loud mistakes first. Look for duplicates in every row, column and box. One of the two is wrong; the clues around them usually tell you which.
- Check the gaps. The empty cells are the ones the previous solver couldn’t fill. Solving them from the clues often shows that a neighbouring “filled” cell has to be something else.
- Prove the rest. For any cell you’re unsure about, ask whether the clues force its digit. If they force a different one, you’ve found a quiet mistake.
Three levels
Rescue comes in Easy, Medium and Hard. Every level leaves you a similar, small amount of work, about 15 cells empty or wrong. What changes is how much you can trust: harder levels give you fewer clues, more quiet mistakes, and a harder puzzle underneath.
Hints that leave you the puzzle
Because the hard part of Rescue is finding the liar, not filling a cell, the mode has three kinds of hint, from gentlest to bluntest:
- Check an area: highlights a row, column or box with a mistake in it.
- Find a wrong number: selects one cell that is wrong, without saying what belongs there.
- Repair a cell: replaces a wrong number with the right one.
Pick the gentlest one that gets you moving, and you keep most of the puzzle for yourself.
Who it’s for
If classic sudoku has started to feel routine, Rescue exercises the same logic from a new angle. It’s also a good way to sharpen your checking: after a few Rescue boards, you’ll catch your own mistakes in classic puzzles much sooner. The techniques are the same as in classic, so Learn Sudoku is still the best place to build them.
