This app was mentioned in 1 comment, with an average of 1.00 upvote
I actually ran into it by random on play store, it's called Sudoku, Pink Pointer is the dev.
I'll try to find a link to it and edit this comment :)
EDIT: https://play.google.com/store/apps/details?id=com.pinkpointer.sudoku is the link to it
It has ads, but they don't bother me so much, you can pay to remove them. Also I have no idea if that's the best app or anything, I started doing sudoku puzzles because I ran into this one by accident :D