There is provided a game system in which areas where operation instruction markers of each player influence each other. The game system 1 determines a division position DP of lane L where an operation instruction marker IM is displayed each time when a predetermined condition is satisfied during a game, and a size of display area DA of the lane of each player based on the determined division position DP. The game system 1 also determines the position of operation instruction marker IM corresponding to each operation timing 20 described in sequence data SD so that the position changes with the progress of music being reproduced, and displays a game image GI where the operation instruction markers IM corresponding to each players P are arranged in the display area DA corresponding to the player P.