I started doing sticker sudoku puzzles with my 3 year old. It was a way for him to do them without being able to write the numbers. Although created for kids, they're fun for adults too. They are for kids who love puzzles and kids who would love puzzles, but don't know it yet. Sticker Sudoku is a new way to solve logic puzzles that just makes it fun!
Warning: They can be addictive.