20 brand new Sudoku-like colourful puzzles daily. Along with unlimited timed puzzles where you have a precise number of moves to solve a puzzle against the clock. A single mistake can mean you can't solve the puzzle.
Simply arrange the colours so there is one (and only one) of each in every row and column and the arrangement matches the clues on the outside (the closest occupied square should match the clue on the outside working horizontally or vertically).
A tutorial gently introduces the rules of the game.