LITS
Place tetrominoes with clever constraints
LITS is a tetromino-placement logic puzzle with a brilliantly layered constraint system. In each outlined region, you must place exactly one tetromino (a shape made of four connected cells) chosen from the four types: L, I, T, or S. All shaded cells across the entire grid must form one connected group. No 2x2 area can be entirely shaded. And identical tetromino shapes in adjacent regions cannot touch orthogonally. These interacting rules create one of the most deeply satisfying deduction puzzles in the Nikoli family.
How to Play LITS
One Tetromino Per Region
Place exactly one tetromino (4 connected cells) in each region. The shape must be L, I, T, or S (including rotations/reflections).
Four Shape Types
L-shape (corner piece), I-shape (straight line of 4), T-shape (T-junction), S-shape (zigzag). Each has multiple orientations.
All Connected
Every shaded cell on the grid must form one connected group through orthogonal adjacency.
No 2x2 Blocks
No 2x2 area of the grid can be entirely shaded. This prevents blocky, featureless shading.
No Same-Shape Touching
If two adjacent regions both contain the same shape type (e.g., both have T-shapes), their shaded cells cannot touch orthogonally.
Four Cells Only
Each region contributes exactly 4 shaded cells. Remaining cells in the region stay unshaded.
Strategy & Solving Tips
LITS solving requires balancing local shape placement with global connectivity and the no-2x2 rule. These techniques address each constraint layer.
- Small regions (4-5 cells) have very few valid tetromino placements — enumerate and analyze these first
- The connectivity rule often forces specific placements: if a region can only connect to the rest through certain cells, those cells must be shaded
- Watch for 2x2 violations: after placing a tetromino, check all nearby 2x2 squares for potential conflicts
- The no-same-shape-touching rule means adjacent regions with L-shapes can't have their shaded cells touch — use this to eliminate options
- I-tetrominoes are the most rigid shape (straight line), making them the most constrained and often easiest to place
- If only one shape type can fit in a region while maintaining global connectivity, that shape is forced
LITS FAQ
What are the four tetromino shapes?
L (corner shape), I (straight line of 4), T (T-junction with 3 in a line plus 1 branch), and S (zigzag). Each can be rotated and reflected into multiple orientations.
Can I use the same shape in multiple regions?
Yes, but if two regions using the same shape are adjacent, their shaded cells cannot touch orthogonally. Different shape types in adjacent regions can touch freely.
Do all 4 cells of a tetromino have to be in one region?
Yes. Each tetromino must fit entirely within its region. No cross-region tetrominoes.
Is LITS solvable without guessing?
Absolutely. Every puzzle has a unique solution reachable through logical deduction. The layered constraints (shape, connectivity, 2x2 rule, same-shape adjacency) provide enough information.
Ready to Play LITS?
Master the layered logic of LITS — where four simple shapes and three elegant rules create one of the most rewarding deduction experiences in all of puzzling.