I want to use open graph to "watch real time sports matches." Built-in watch action-type seems to support only TV-show, movie, and video and doesn't support game match.
Could anyone tell me how to extend built-in watch action-type? And if possible, please show me how to extend built-in object-types?
Built-in game match object type requires sores and players. But you can not know the box scores untile the game ending, actually.
Open Graph doesn't support extending actions today -- instead, try creating a custom watch action and game (or match) object.