Kenken is a pencil and paper or online solo game like a take off of sudoku. It deals with numbers and the 4 functions -add subtract devide multiply. Google kenken game and there you are. They start easy and leap frog quickly to monsters. But there are printed versions at your grocery store mag stand. Online games seem more difficult than paper ones. If you buy the book get a pencil with a big erasure. And happy gaming!!!!!
Sudoku is online too. I do one a day