The ornamental design for a gameboard, as shown and described.
FIG. 1 is a top plan view of a gameboard, showing my new design, the broken
line showing of the word "Free" is for illustrative purposes only, and
forms no part of the claimed design;
FIG. 2 is a bottom plan view thereof;
FIG. 3 is a side elevational view thereof, the opposite side being a mirror
image; and
FIG. 4 is an end elevational view thereof, the opposite end being a mirror
image.