Dark Portal
Rules:
- Classic Sudoku:
Every row, column and 3x3 box must contain every number from 1 to 9.
- Palindrome Lines:
Digits along a grey line read the same backwards and forwards.
- Arrows:
Numbers along an arrow sum up to the total in the circled cell.
- Kropki:
Digits separated by a white dot are consecutive; digits separated by a black dot have a 1:2 ratio.
Play it online in SudokuPad.
This puzzle is also on Logic Masters Germany.