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Place one tetromino (L, I, T, or S shape) in each region so shaded cells are all connected, no 2×2 block is fully shaded, and identical tetrominoes are never adjacent.
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About LITS
LITS is a Nikoli puzzle where you place one tetromino (L, I, T, or S shape — four connected cells) in each region of the grid. The placed tetrominoes must form a single connected group, may not contain any 2×2 block of shaded cells, and same-shaped tetrominoes — even in different orientations or reflections — may not be adjacent.
The shape-matching constraint is what makes LITS distinctive. You cannot freely choose which tetromino to place in each region: if an L tetromino is already adjacent to a region’s boundary, that region cannot also use an L. This forces careful global coordination between neighboring regions.
LITS stands for the four tetromino shapes available: L, I, T, S. It’s one of Nikoli’s most creative puzzle concepts, requiring both the spatial intuition needed to fit tetrominoes into irregular regions and the logical deduction needed to avoid constraint violations.
Start with regions that have very few possible tetromino placements — a narrow corridor might only accommodate an I-tetromino. Once a region’s shape is locked in, propagate the same-shape exclusion to all adjacent regions to rapidly narrow their options.
Frequently asked questions
What is LITS?
LITS is a logic puzzle where you shade a tetromino (4-cell shape) in each region. All shaded cells must be connected, no 2×2 area can be fully shaded, and two identical tetrominoes (same letter) cannot share an edge.