Normal 6x6 rules apply for each of the 6x6 grids separated by thick black lines.
Each 6x6 grid has a different line constraint (lines can satisfy multiple constraints, but all lines in a 6x6 grid must satisfy the constraint for the grid). Lines that enter multiple grids must satisfy all constraints for all the grids entered.
The line constraints are:
RENBAN: Digits along a renban must form a set of consecutive digits in any order.
REGION SUM LINE: Box (and grid) borders separate each region sum line into segments with the same sum. (Lines can have only one segment, e.g. they don't cross any borders)
ENTROPIC LINE: Every set of three (3) adjacent digits along an entropic must have digits from each of the following sets: low (12), medium (34), and high (56).
GERMAN WHISPER: Adjacent digits on a german whisper must differ by at least 3.
Sudokupad:
https://sudokupad.app/1y510cvwtx