public void run() {
            tiempoActual = System.currentTimeMillis();
            while (true) {
                if (!pausa && !gameOver) {
                    checaColision();
                    actualiza();
            }
                repaint();
                try {
                    Thread.sleep(50);
                } catch (InterruptedException ex) {
                    System.out.println("Error en " + ex.toString());
                }  
            }
        }