Sudoku variant · rules and tips

Fog of War Sudoku

The grid lies under fog. You see only the given digits and the cells beside them. A correct placement clears the fog nearby; a wrong one leaves it exactly where it was. Knowledge, as ever, is earned one step at a time.

Get it onGoogle PlayPlay Fog of War Sudoku on the web
Professor Cryptic, the owl who teaches in the app
Professor Cryptic explains the rule

The Professor's tips

How do you solve Fog of War Sudoku?

01 / Warm up

Start on a 4 by 4 grid

  • Begin with the cells you can see, for they are the whole of your evidence. Work outwards from what is already in front of you.
  • Each correct placement reveals its cell and the neighbours beside it. String those reveals together and the grid opens up.
  • If you are stuck, look among the visible cells for a digit that is forced. The fog hides the board. It cannot hide the logic.
02 / Level up

Then try a 6 by 6 grid

  • Each reveal covers only a small area on a 6 by 6 grid, so plan a route that uncovers the regions you actually need.
  • Work at the edge of the fog. Solving the cells along that boundary is what uncovers the next layer.
  • Notes matter more here than anywhere else, because you are tracking candidates through a small and shifting window.
  • Trust the deduction. If the visible constraints force a digit, place it, and the grid will reward you by showing you more.

The rule, drawn

What does Fog of War Sudoku look like?

  1. Fog of War Sudoku rule illustration, step 1 of 3
  2. Fog of War Sudoku rule illustration, step 2 of 3
  3. Fog of War Sudoku rule illustration, step 3 of 3

Start with a single square

Where can you play Fog of War Sudoku?

Fog of War Sudoku is one of the 17 variants in Cryptic, each with a lesson and unlimited puzzles.

Get it onGoogle PlayPlay on the web