Thisappallowsuserstoplaytheexciting"Sandwich"variantofSudokuforfreewithnoads.Alsoknownas"1through9Sudoku",thisvariantgivesadditionalcluestellingtheuserthesumsofthenumbersbetweenthe1and9ineachrowandcolumnofthepuzzle.Forinstance,ifarowcontains2and6betweenthe1and9,theadditionalcluewouldshowthenumber8.Thisappisfreeandmayincludeadditionalrequestedfeaturesinthefuture.