A dropleaf would be the easiest, you can either create a swiveling support on both sides with a peg for mounting either free floating a short distance like 1 feet each side, or with a leg to support the weight, you could add wheels to the legs or make them hinge as well and preferably make the angle at which they rest on the swivel stop it from collapsing again.
Second way would be to have the table slide outwards and let a panel lay in the created void, preferably on the apron, which can be used to mount or create the sliding mechanism with.
Third way would be dependent on the height of the table and the dropleaf, create a pair of legs and let it hinge underneath the dropleaf, when it is time to game you slide in the apron, you might need to mount the legs so they can rest next to each other and some overhang is needed before you start the dropleaf.