How to play
- Thick walls split the grid into regions. Shade exactly four cells in every region, joined side to side: a tetromino.
- All the shaded cells connect into one piece.
- No 2×2 block is all shaded.
- Two tetrominoes of the same shape can’t touch by an edge. Rotations and reflections count as the same shape, so the shapes are L, I, T and S.
- Tap a cell to shade it, again for a dot that marks it unshaded, again to clear. Drag to paint.
Keyboard: arrows to move, space to cycle, s shade, d dot, 0 clear, Ctrl+Z undo, Ctrl+Shift+Z redo.
Learn how to solve it