This is my first-ever sudoku. I've had this idea in my head for a while now, and it fit the theme of the CtC Discord server's monthly prompt ("riddles") so perfectly I had to finally sit down and create it. I've never seen a puzzle quite like this before so I'm hoping it's original.
For her birthday, Cheryl created a sudoku puzzle for her friends Mark and Simon. Mark and Simon are both sudoku experts and perfect logicians, so Cheryl decided to play a trick on them—she withheld one of the puzzle’s given digits from each of them to see if they would still be able to solve it. For Mark, she provided the value of the blue cell (labeled “M”) and withheld the value of the orange cell (labeled “S”). For Simon, she provided the value of the orange cell and withheld the value of the blue cell.
Knowing all this, Mark and Simon both went off on their own to try to solve the puzzle and afterwards came together to discuss their findings.