[quadrata]

The clues in this new style of puzzle depend on the number of primes in the two cells. A numeric clue indicates that exactly one of those numbers is prime and reveals the difference of the two numbers. A numberless clue indicates that either both or neither of those two entries are prime numbers. (Remember that 1 is not a prime!)

For a solution and more info visit: https://quadratablog.blogspot.com/2021/ ... edoku.html