In Threes!, you slide tiles on a 4x4 grid to combine numbers that are multiples of three. Start by merging 1 and 2 tiles to form a 3, then combine two 3s to make a 6, two 6s to make a 12, and so on. Swipe up, down, left, or right to move all tiles in that direction, with a new tile appearing on the opposite side. The color of the incoming tile is shown onscreen, allowing you to plan your moves. The game ends when no moves are possible, and your score is calculated based on the tiles on the board. Focus on creating larger numbers while keeping the grid open to avoid getting stuck.