The ornamental design for a gameboard, as shown and described.
FIG. 1 is a top perspective view of a game board showing our new design;
FIG. 2 is a top plan view thereof; and,
FIG. 3 is a top perspective view of the game board, shown in use.
The dash-dash (evenly sized) broken lines showing a 10 of diamonds playing card in FIG. 3 depicts environmental subject matter that forms no part of the claimed design, while the remaining dash-dash (evenly sized) broken lines shown in the drawings depict portions of the game board that form no part of the claimed design.
The dot-dash-dot (unevenly sized) broken lines shown in the drawings depict the bounds of the game board that form no part of the claimed design.