Every game can be played on a (sufficiently complex) table. Ok, so what's on the table? That's the "Board", or "representation of the game's state". This could be a map, actual board, or how the galaxy looks at a given point in time. Everything that changes the game's state goes through the Board's interface.

Now, within the Board, you have some number of "Piece"s. These are the things that are moved around on the Board. The only hierarchy allowed to touch a Piece is the Board.

Now that you have your gamestate, you need things that change the gamestate. Generally, this is either humans or computers. So, create a connection to some person and, if needed, a connection to some AI "process". These connections will have the same basic interface. Something along the lines of a SetupConnection(), GetMove(), DisplayBoard(), and EndConnection().

After that, it's just data structures to help you make your life easier. For example, if you were building a MUD, you'd have a Thing class. Then, Thing::Alive and Thing::Inanimate would be its children. Then, Thing::Inanimate::Weapon vs. Thing::Inanimate::Armor, and so on. These would be examples of a Piece hierarchy.

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.