How to play

Stostone — ストストーン — is a Nikoli puzzle about stones that fall.

The bold lines divide the grid into rooms. Shade cells to build one stone in every room.
A stone is a single connected block of shaded cells, and it never leaves its own room.
A number in a room says how many cells that room’s stone covers. A room with no number holds a stone of any size.
Stones in different rooms never touch side by side. Corner to corner is fine, and cells of one stone touching each other is the whole point.
Now let the stones fall straight down, each keeping its shape. They must land filling the bottom half of the grid exactly — no gaps below the halfway line, nothing left above it.

Tap a cell: shade it > mark it empty > clear it. Half the grid ends up shaded, and the counter keeps track.

On the name

Stostone is a Nikoli puzzle. English puzzle books print it as Stostone or Sto-stone; in Japanese it is ストストーン. The spelling changes, the puzzle does not — rooms, one stone in each, and a drop to the floor.

The rules in full