public void spawnNPC() {
        if (grabEnemyPerFrame > 0) grabEnemyPerFrame--;
        if (spawnModifier < (60 * 60)) spawnModifier += growthRate;
        // Spawn Enemy per frame in growth rate
        
        if (grabEnemyPerFrame <= 0) {
            NPC n = new NPC(Math.random() * ImageManager.board.getWidth(), 0, 0, 10, true);
            NPC.add(n);
            ImageManager.addEnemy(n);
            // Enemy shooting rate 50%
            if (Math.random() >= 0.5) {
                Bullet b = new Bullet(n.getX() + 10, 20, 0, 10, true);
                b.setDirection(1);
                b.setMoveSpeed(3);
                BulletNPC.add(b);
                ImageManager.addDownBullet(b);
            }
            if (spawnModifier < (60 * 60))
                grabEnemyPerFrame = EnemyPerFrame - ((int)(spawnModifier/60));
        }
                
    }