The Express occassionaly publishes "Sudoku welterweight" puzzles, which are five 9x9 grids that overlap in the shape of a quincunx. It's also known as "Gattai 5" or "Samurai Sudoku."
They look difficult, but they are actually easier than a traditional Sudoku. It takes five times as long to complete, due to the sheer size. But the overlap helps speed up the process of elimination, which is the essence of the game.