public void addPlayer(Player player) {
    if(state == GameState.BEFORE) {
      if(players.size() < 2) {
        if(players.size() == 0) {
          player.setColor(PieceColor.BLACK);
        } else {
          player.setColor(PieceColor.WHITE);
        }
        
        players.add(player);
        
        setChanged();
        notifyObservers(player);
      }
    }
  }