LITS

LITS is a type of shading logic puzzle, in which solvers must shade tetrominoes in marked regions, such that no 2x2 region is fully shaded, tetrominoes across marked regions must be different, and all shaded cells are connected.

Background

LITS was first introduced in Puzzle Communication Nikoli #104 in 2004. The original name for the genre was ヌルオミノ ("Nuruomino"), derived from ヌル ("to paint") and オミノ ("-omino"). The genre was renamed to LITS in Volume #112 in 2005, after the four permissible tetromino shapes in the genre (due to the 2x2 shaded rule, the O tetromino cannot show up).

A board game based on the LITS genre, Battle of LITS, was designed by Grant Fikes and was released in 2011.

Puzzle Application

An example LITS puzzle

The solution to the above puzzle

TO DO

Strategy

• A region of size four is entirely shaded. Slightly larger regions may still have certain cells that must be shaded. (for instance, if a cell isn't shaded, it would break a region into regions of size 3 or smaller, which could not fit a tetromino)
• Due to the 2x2 shaded rule, two shaded cells next to each other form a "virtual wall" that cannot both be shaded.
• Certain regions may restrict the type of tetromino to a single type. If multiple such regions are next to each other, considering all of these regions together may provide additional constraints on placement.
• For large regions, connectivity may also place significant constraints on placement.

Examples

TO DO

See Also

• List of LITS puzzles