The ornamental design for a gametable covering, as shown and described.
The ornamental design is intended for use on a table such as that used for playing a casino wagering card-type game and readily adaptable to any gaming platform.
FIG. 1 is a top view of a game table covering showing the incorporation of the Applicant's design; and,
FIG. 2 is a side view of the same game table covering which is of conventional thickness.