Sure, here’s how it works.
- Under Section 5, you owe a royalty on all revenue for a Product (unless a royalty exclusion applies).
- Product is defined in Section 25. High level, it’s any product made using or which includes the Unreal Engine, or any part of it.
So in this case, part of the game is made with UE4, and that makes it a Product, which makes it subject to royalty.