Kakuro++ Cross Sums comes from Chaviro Software.  I've been a fan of Kakuro since 1989 when it was called Cross Sums.

This particular game has 1430 levels in 11 categories of difficulty.
It's free and there are no ads.https://itunes.apple.com/us/app/kakuro-cross-sums/id1445001139"mt=8

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