public override void Update(GameTime gameTime)
        {
            // Get rid of unneeded objects.
            RemoveObjectsOutsideScreen();

            currentGameTime = (float)gameTime.TotalGameTime.TotalSeconds;

            foreach (GameObject go in gameObjects.FindAll(x => x.FlaggedForRemoval))
            {
                scriptManager.AbortObjectScripts(go);
                gameObjects.Remove(go);
            }

            foreach (GameObject go in gameObjects.FindAll(x => x.IsNewObject))
            {
                go.IsNewObject = false;
            }

            foreach (Animation a in animations.FindAll(x => x.FlaggedForRemoval))
            {
                animations.Remove(a);
            }

            // Populate the quadtree in preparation for collision checking.
            quadtree.Clear();

            foreach (GameObject go in gameObjects.FindAll(x => !x.IsNewObject))
            {
                go.Update(gameTime);
            }

            foreach (GameObject go in gameObjects.FindAll(x => !x.IsNewObject))
            {
                quadtree.Insert(go);
            }

            foreach (Animation a in animations)
            {
                a.Update(gameTime);
            }

            scriptManager.Update(gameTime);
            collisionDetection.BroadphaseCollisionDetection();

            levelManager.Update(gameTime);

            if (Experience > 0)
            {
                if (!ExperienceDecayPaused)
                {
                    Experience -= ExperienceDecay * (float)gameTime.ElapsedGameTime.TotalSeconds;
                    if (Experience <= 0)
                    {
                        ResetRank();
                    }
                }
                else if (ExperienceDecayPaused && ExperienceDecayPauseDuration > 0)
                {
                    ExperienceDecayPauseDuration -= (float)gameTime.ElapsedGameTime.TotalSeconds;
                    if (ExperienceDecayPauseDuration <= 0)
                    {
                        ExperienceDecayPaused = false;
                    }
                }
            }

            CheckExtend();
            AudioManager.PlayQueuedSoundEffects();
        }