Your goal in 90 Grad is to either push the opponent's "queen" marble from the board or to move your queen to the central square. Each player starts with seven marbles: one queen, with the queens being placed in opposite corners of the board, and six regular marbles, with these marbles flanking the queen three on each side. On a turn, a player moves one marble in an orthogonal direction, and the marble moves as many spaces as the number of marbles in the row perpendicular to the direction being moved. Players alternate moves until one of the winning conditions is achieved.