The ornamental design for game board component, as shown.
FIG. 1 is a perspective view of a game board component;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a bottom view thereof;
FIG. 7 is a front reference view illustratively depicting the formation of a game board when two of the game board component halves are joined together; and,
FIG. 8 is a side reference view illustratively depicting the manner in which the game board component halves can be stacked up.
The exemplary broken line showing of additional game board component halves in FIGS. 7 and 8 is for illustrative purposes only and forms no part of the claimed design.