The grid is split into rectangular rooms. Shade some squares so that every room with a number has exactly that many shaded squares; rooms without a number can have any amount.
Shaded squares may not touch along a side, and all the white squares must join up into one connected area. Finally, a straight run of white squares, across or down, may not pass through more than two rooms — it can’t cross two walls.
Start with rooms whose numbers are big for their size, then use the two-walls rule wherever a long white line is forming.
Shade squares so each numbered room has that many shaded, shaded squares never touch, white squares stay joined, and no straight white line crosses two walls.
The full guide, with a worked example and common mistakes: How to play Room Shade.
No — they can have any number of shaded squares, including none, as long as the other rules hold.
No — it is only about straight runs of white squares.
Yes — every puzzle here is checked to have exactly one solution.
Open the Room Shade Solver, draw the rooms, type the numbers and press Solve.