Author: Vladimir Portugalov
Shade some empty cells black to create a single connected wall. No 2x2 square can be completely shaded. Cells with numbers can't be shaded. All unshaded cells form islands. Each island contains exactly one numbered cell which equals the size of the island.
Grid control: Click the mouse button at the selected cell to change the color of the cell. Second click will put auxiliary cross sign, which doesn't affect correctness of the solution, but helps visually. You can also drag the content of one cell to another with the mouse. More details about grid control are at the help page.