How to solve LITS

LITS gives you a grid split into regions by thick walls. You shade exactly four cells in every region, joined side to side: a tetromino. Together they make the letters L, I, T and S.

Three rules join the regions up. All the shaded cells connect into one piece. No 2×2 block is all shaded. And two tetrominoes of the same shape never touch by an edge, counting rotations and reflections as the same: the same-shape rule.

Every puzzle here has a unique solution, reachable by logic alone.

Start with the smallest regions. A region of four cells is its own tetromino, as long as it is an L, I, T or S. A region of five or six cells often has only one or two fits.

Shade what every fit shares, and dot what no fit can reach. Then check each shaded cell’s 2×2 squares: three shaded cells in a square make the fourth unshaded.

Name each finished tetromino. A neighbour can’t take the same letter where they would touch. And keep the shading in one piece: a fit that strands some shading is out.