@Subscribe
  public void onStart(GameStartedEvent event) {
    Connect4Board board = Connect4World.getContext().getBoard();

    // Velena funktioniert nur bei 2 Spielern ...
    if (getContext().getEntities(Connect4Player.class).size() != 2)
      throw new IllegalStateException("players != 2");
    // ... 7x6 Spielfeldern ...
    if (board.getWidth() != Connect4Board.DEFAULT_WIDTH
        || board.getHeight() != Connect4Board.DEFAULT_HEIGHT)
      throw new IllegalStateException("board != 7x6");
    // ... und genau 4 Sieg-Chips
    if (Connect4World.getContext().getWin() != 4) throw new IllegalStateException("win != 4");

    moveCode = new String();
  }
  @Override
  public int move() {
    Connect4Board board = Connect4World.getContext().getBoard();

    int move = random.nextInt(board.getWidth());

    return !board.isFull(move) ? move : move();
  }