LITS+ (515)

Shade some cells in the grid so that there are exactly 0 or 4 shaded cells in each outlined region. In each area, the shaded cells must be orthogonally interconnected, forming a tetromino L, I, T or S. The tetrominoes can be rotated and/or reflected. All shaded cells must be connected orthogonally, and there cannot be any 2x2 square consisting entirely of shaded cells or of unshaded cells. No two tetrominoes of the same shape (even if reflected or rotated) can share an edge.

Reference: WPC 2016 (65)