The puzzle you were pointed at is an Arrow Heart Sudo-Kurve.

SPECIAL REGIONS: Unlike a standard sudoku, the rows here can bend along the indicated curves. Each row contains exactly 9 cells.

EXTRA CONSTRAINTS: There are some arrows in the grid. The digit that sits in the circled cellshould be equal to the sum of all the digits along the rest of the path of the arrow. Numbers may repeat in a sum, but cannot otherwise violate a "unique number" constraint.