Unreal announced yesterday that Unreal Engine 4 is now free* for everyone. What this means is that you can download and use the software to make a game for free. The only time you have to pay them money is if you are successful, paying 5% gross if you make more than $3,000 per quarter.
Unreal Engine 4 is now available to everyone for free, and all future updates will be free!
You can download the engine and use it for everything from game development, education, architecture, and visualization to VR, film and animation. When you ship a game or application, you pay a 5% royalty on gross revenue after the first $3,000 per product, per quarter. It’s a simple arrangement in which we succeed only when you succeed.
This is the complete technology we use at Epic when building our own games. It scales from indie projects to high-end blockbusters; it supports all the major platforms; and it includes 100% of the C++ source code. Our goal is to give you absolutely everything, so that you can do anything and be in control of your schedule and your destiny. Whatever you require to build and ship your game, you can find it in UE4, source it in the Marketplace, or build it yourself – and then share it with others.
Read more about it here:
https://www.unrealen...com/blog/ue4-is-free 
