Sudoku Expert, Hard, Easy, also known as Sudoku 4-in-1, is a logic-puzzle game based on the newspaper Sudoku classic. It offers four levels of gameplay (Easy, Medium, Hard and Expert) on a 9x9 wooden board hanging from loops of rope. Although the two titles make the game sound confusing, it's the opposite.
The player arranges numbered tiles on a grid broken into nine 3x3 subgrids across rows and columns. They complete each line with the numbers 1 through 9 using tiles below the board. They must never allow the numbers to repeat horizontally, vertically or within the subgrids.
The game doesn't penalize the player for failing to find a solution within a specific amount of time. Instead, the player attempts to beat their last-best time with each new game.
Sudoku 4-in-1 fills the board with numbers from the start as hints. The wooden board in Easy mode contains the most prefilled numbers. The prefilled numbers decrease with the more difficult modes.
All the numbers are black. When placed, a tile number transforms from a shade of brown to a different color. If the player places a tile incorrectly, the game makes it flash as a warning. The player can fix the problem by dragging the correct tile to the position to overlap the incorrect one.