London Underground
- Kropki dots
- Region sum lines
- Whisper lines
The brief
Normal sudoku rules apply.
Digits along the grey (Northern) and blue (Victoria) lines have an equal sum N within each box they pass through (Region Sum). N may be different on each line.
Digits along the green (District) line must differ by at least 5 (German Whisper).
Digits along the red (Central) line must be 5 or greater.
Any set of three sequential cells along the yellow (Circle) line must contain a low (1-3) digit, a middly (4-6) digit, and a high (7-9) digit (Entropic).
The pink (Hammersmith & City) line contains a set of the digits 1-9 in any order (Renban).
The digits separated by Victoria Station (black dot) have a 2:1 ratio (Kropki).