Barrier LITS is a variant of LITS, in which the cells in a grid are split into either shaded or unshaded.
The objective is paint four connected cells in each shape, subject to the following rules:
- No two of the same tetrominos, including rotations / reflections are allowed to touch.
- All painted cells must connect upon completion.
- No 2x2 area of painted cells is allowed.
- Some shapes include barriers between cells, tetrominos are not allowed to appear on both sides of the barrier.
A standard 10x10 Barrier LITS and its solution.