KeyboardState lastKeyState;

        bool isFadeIn = false;
        float alphaValue = 0.0f;

        protected override void Update(GameTime gameTime)
        {
            KeyboardState ks = Keyboard.GetState();

            // TODO: Add your update logic here
            if (gps.Buttons.Back == ButtonState.Pressed)
                this.Exit();

            if(ks.IsKeyUp(Keys.Space) && lastKeyState.IsKeyDown(Keys.Space))
            {
                isFadeIn = true;
            }

            if (isFadeIn)
            {
                alphaValue += (float)gameTime.ElapsedGameTime.TotalMilliseconds;
                if (alphaValue >= 1.0f)
                {
                    alphaValue = 1.0f;
                    isFadeIn = false;
                }
            }
            else if (alphaValue > 0.0f)
            {
                alphaValue -= (float)gameTime.ElapsedGameTime.TotalMilliseconds;
                if (alphaValue <= 0.0f) alphaValue = 0.0f;
            }

            base.Update(gameTime);
        }

        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);

            // TODO: Add your drawing code here
            spriteBatch.Begin();

            spriteBatch.Draw(textureSprite, destRect, sourceRect, new Color(Color.White, alphaValue));

            spriteBatch.End();

            base.Draw(gameTime);
        }