SudoKanard

 Between Killer Sudoku Classic Sudoku rules apply. The digits in a cage must sum to the number printed in its corner. Digits may not repeat within a cage. Cells along lines between two filled circles must have values strictly between those in the circles. Solve on Penpa: https://tinyurl.com/yahtleg3 Solve on CtC: https://bit.ly/3qKzE8e Solution on video: https://www.youtube.com/watch?v=_-piQrp8pp4

 Between Quadruple Sudoku Standard Sudoku rules apply. Digits in a small circle must appear at least once in the surrounding four cells. Digits on a gray line must lie strictly between the digits in the grey circles at the ends of the line. Solve on Penpa: https://tinyurl.com/y8fy62ug Solve on CtC:  https://bit.ly/3NlIS4A

 Antiknight Quadruples Sudoku Normal Sudoku rules apply. Place the digits 1 through 9 in each empty cell. Digits must not repeat within the same row, column, or box. Circled digits where four cells meet must be present as values in those four cells. Digits must not repeat in cells that are a chess knight's move apart. Solve on Penpa: https://tinyurl.com/ydcqof5n Solve on CtC:  https://bit.ly/3CxYxJf

 Antiknight Sudoku Standard Sudoku rules apply. Each pair of cells separated by a chess knight's move must contain different digits. https://tinyurl.com/y729cq4q