SudoKanard

 Quadruple Sudoku Standard Sudoku rules apply. Digits in a circle must appear at least once in the surrounding four cells. Solve on Penpa: https://tinyurl.com/yxuobgtg Solve on SudokuPad: https://tinyurl.com/36v2ypwu

 Killer/X-Sums Sudoku Apply classic Sudoku rules. The digits placed in each marked cage must sum to the total given in its top-left corner. Digits must not repeat in cages. Each clue outside the grid indicates the sum of the first digits placed in the corresponding direction, where X is equal to the first digit placed in that direction. Solve this puzzle on Penpa: https://tinyurl.com/2rybmlhj

 X-Sums Sudoku Standard Sudoku rules apply. Each clue in the margin is the sum of the first X digits in the corresponding direction, where X is the digit next to the clue.   Penpa link to solve online: https://tinyurl.com/2fzntxej