Squishdoku: Place the digits 1 through 9 once each in every 3x3 box, without repeats in any row or column. Cells on region borders (dashed lines) are shared between multiple boxes.
Dutch Flat Mates: Every 5 in the grid must have a 1 directly above it or a 9 directly below it. It may have both, but it doesn’t need both.
Kropki Pairs: Digits separated by a black dot are in a 1:2 ratio. Digits separated by a white dot are consecutive. Not all dots are necessarily given.
Lösungscode: Digits in row 1