Stostone rules copied from Nikoli:
- Fill in the colored cells with the following rules.
- The areas enclosed with bold lines are called "Rooms." The number in a room shows the number of continuous black cells in that room. Rooms with no number may have any number of black cells.
- Black cells cannot connect across bold lines, vertically or horizontally.
- When all stones are "dropped" straight down (empty cells under colored cells deleted) the stones must fill the bottom half of the grid without empty cells (then dropped stones may cross and connect across bold lines).