What are alphadoku puzzles? Alphadoku puzzles are Sudoku like puzzles that use letters instead of numbers to create the brain teaser. These brain teasers use the same deductive and inductive reasoning, problem solving strategies, and mental work required of logic puzzles. They are like Sudoku puzzles with a twist. This category is further broken down into easy, medium and hard alphadoku puzzles. Check back often for new puzzles.