Epic Games has announced that Unreal Engine royalties are now waived on the first $1 million in-game revenue. This change was announced on May 13, 2020.
The welcome change to developers and designers is an increase from the previous cap of $100,000 in-game revenue.
This, of course, means you can download and use the game engine to build games for free as always, except now you do not need to pay royalties until you make the first $1 million in gross revenue. The royalties remain at 5%.
Unreal Engine is still 100% royalty-free if you use it to create internal or free projects, or to develop linear content or custom projects for clients, but not for publishing off-the-shelf offerings.