It's "weaker" and different constraints than a sudoku.
A regular sudoku requires all 1-9 numbers in three containers: in the box, in the row and in the column.
This variant still has the 1-9 boxes, but instead of rows and columns it has lines, and the lines do not encompass all numbers 1-9. They only say numbers can't repeat on that line. You can't use completeness for the lines (It would be something like "all numbers 1-9 must occur along a line").
I suspect that the missing completeness is a drawback of this sudoku variant, it makes it a bit less interesting in the long run.
A regular sudoku requires all 1-9 numbers in three containers: in the box, in the row and in the column.
This variant still has the 1-9 boxes, but instead of rows and columns it has lines, and the lines do not encompass all numbers 1-9. They only say numbers can't repeat on that line. You can't use completeness for the lines (It would be something like "all numbers 1-9 must occur along a line").
I suspect that the missing completeness is a drawback of this sudoku variant, it makes it a bit less interesting in the long run.