Think Twice is played on two 6x6 grids each filled with the numbers 1-36 - each player fills one grid as they wish before the game starts. On a turn a player selects one of the numbers and fills in the corresponding space on each grid. This continues until all the spaces are filled. Players score for lines of four, five, and six in any direction. In addition, bonus points are awarded on each grid for the player with the largest connected group of spaces: they score the difference in size between this and the other player's largest group on that grid.