Normal sudoku rules apply. Divide the grid into 4 sections of orthogonally-connected cells such that each section shares an edge with every other section and no 2x2 area is occupied by only one section. Cells on the same line belong to the same section. Each section has a different constraint, which ALL of its lines must obey. The constraints for each section are: i) RENBAN: Digits on a line do not repeat and form a consecutive set, in any order; ii) PALINDROME: The digits along a line read the same forwards and backwards; iii) GERMAN WHISPER: Adjacent digits on a line must have a difference of at least 5; iv) REGION SUM: Along a line, if it crosses a 3x3 box border, each line segment within a different 3x3 box must sum to the same total. The sum may be different for different lines.