iGaming Business – Social casino studio Plumbee has announced the addition of player tournaments to the Facebook version of its Mirrorball Slots application. Players will be able to access the new tournaments via a lobby within the app, allowing them to select one of four different stakes in which to compete with others in a ‘Battle Royale’, with the top two players winning virtual cash prizes. In addition, Plumbee has also introduced a new free-to-enter tournament where players can win coins to spend in other tournaments or slot games in the main Mirrorball Slots game. Dave Wright, games producer at…