Update README.md

Author: adamgraham

README.md

@@ -3,7 +3,7 @@
 > Flappy Bird is a mobile game developed by Vietnamese video game artist and programmer Dong Nguyen. The game is a side-scroller where the player controls a bird, attempting to fly between columns of green pipes without hitting them.
 
 - **Difficulty**: Beginner
-- **Topics**: Side Scrolling, Infinite Generation
+- **Topics**: Side Scrolling, Infinite Generation, Parallax
 - **Version**: Unity 2019.4 LTS
 - [**Download**](https://github.com/zigurous/unity-flappy-bird-tutorial/archive/refs/heads/main.zip)
 - [**Watch Video**](https://www.youtube.com/c/zigurous)