Rules -- Tetra Firma

Tetra Firma was invented by the Japanese puzzle company Nikoli (under the name LITS, FKA Nuruomino).

1. Shade in a single tetromino within every region of the grid.
2. No two congruent tetrominoes may share an edge, even if they are rotated or reflected versions of each other.
3. The black cells must all be connected to each other through their edges. No 2x2 cell area within the grid can contain all black cells.

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