In each column and region, the digits 0-9 appear exactly once each.
In each row, a set of six different digits appear exactly once each. No two rows share a set of digits.
The snowball regions (gray boxes) contain the same digits in the same arrangement plus or minus a constant value (which may differ per snowball region).
The cells indicated with four diamonds do not contain digits one less than nor one greater than any orthogonally adjacent cell.
The cells with shaded circles do not contain a 9.