Daily Wordoku is also sometimes called "Letter Sudoku". Is like a Sudoku game but it uses letters instead of numbers. The basic rules are absolutely same as in sudoku, but you need to fill out missing letters instead of numbers. You need to fill every row, every column and 3x3 block with each given letter exactly once. 

Another difference in Wordoku that in diagonal cells from top left to bottom right should spell a common English word. This creates an interesting twist in solving this word puzzle game, as you can take possible words, or letter ordering into account when solving the puzzle. 

In Daily Wordoku it is normal repeat the same letter in diagonal word, as long as it not breaks main Sudoku rules. Letters are not repeated within the same block, row or column.