Regional Bat
- Region sum lines
- Parity lines
The brief
Normal rules apply. Blue lines are Region sum lines, i.e. the digits on a blue line sum to the same value in each 3x3 region the line passes through. If a blue line enters a 3x3 region more than once, each segment has to be considered separately. Adjacent digits on a red line must alternate between odd and even. Battenburg: Whenever 2 odd and 2 even digits form a 2x2 checkerboard pattern, a Battenburg marking is given. If there is no such marking, the above pattern is not allowed.