Had a go, got the bottom 5 rows than was lost.

It's not even close to solvable without massive hints.

The 6 and 8s make a box. The 11 starts in r6 and the 13 in r3.
You then have 2 lines of single dots from r1,c7 to r7,c1 and r1,c11 to r11,c1.

Multiple possible solutions. Thank you for the hints, Teesea.

Tips for making puzzles: Lots of single squares in a diagonal line can have multiple possible solutions. Making an inverse version of the puzzle often helps for characters like this. There's also an option to test solve your puzzle, which is a great way to eliminate ambiguous squares prior to submitting the puzzle.

Thanks for the hints - imposssible otherwise.

And I googled the sign.

The 13 starts in row 4.

Thanks for the hints, Teesea, and thanks for the clarification, Poppy!

Awful ...

Terrible - too many possibilities.

Sucks.

Thanks for the hints not possible without them a waste.