LITS ("Nuruomino") is a logic puzzle created by Naoki Inaba (Japan). The puzzle consists of a rectangular grid of any size divided into regions. The goal is to blacken exactly four connected cells in each region, to form an L, I, T, or S tetromino.
The tetrominoes may be rotated or mirrored. When two tetrominoes in adjacent regions share an edge, they must not be of the same type. All tetrominoes must form an orthogonally contiguous area. The tetrominoes must not cover an area of 2 x 2 cells.
Cross+A can solve puzzles from 4 x 4 to 30 x 30.
Double LITS: each region must contain two tetrominoes. These two tetrominoes within a region cannot touch each other horizontally or vertically (only diagonally); they can be the same or different shapes.
