I only make 2d games, but I can't think of any way to implement the jam's theme. I was really excited to take a part in this jam, but now I don't think it's possible.
We would love to see anything you create and there are definitely creative ways to incorporate the game theme into your game. In the past, contestants have found that they can interpret the theme in multiple ways!
If you're stuck, take another look at the video- there are several different examples of "reflection" and "reflective properties" meant to help you think outside of the box!