It’s a mashup of Easy as ABC and regionless LITS.
Standard regionless LITS rules:
- The shaded area must be continuous
- There can’t be any 2×2 blocks of shaded cells
- The shaded area must be tileable with LITS tetrominoes such that no two tetrominoes of same shape touch
- No row or column may have two tetrominoes of the same shape in it
- The clues along the edges tell the shape of the tetromino that is first seen in that column or row
- (L and J tetrominoes and S and Z tetrominoes aren’t distinguished)
- A bolded line between clue cells means the two cells can’t see the same tetromino
- No line between clue cells means the two cells see the same tetromino
- A dashed line between clue cells means the two cells may see the same tetromino, but not necessarily
Hopefully I was clear with the rules.