Returns a boolean value indicating whether or not the game is over, based off win conditions. These conditions include whether or not one of the players in the game has any live units left. \n\n
\b Exceptions: \n
- The function requires that the players passed through are valid player objects in the game and are non-null.
- The function assumes that the two players being passed through are both different objects.
\param player1 Player 1 of the current game.
\param player2 Player 2 of the current game.
- The function requires that Player1 and Player2 stored in GameState are non-null.
- The function assumes that the two players stored in GameState are both different objects.