You can try out this Experimental feature, but we do not recommend shipping projects with it.
This feature is Experimental.
Features are sometimes made available in an Experimental state so you can try them out, provide feedback, and see what we are planning. We do not recommend shipping projects with Experimental features. Please keep in mind that we do not guarantee backward compatibility for assets created at the experimental stage, the APIs for these features are subject to change, and we may remove entire Experimental features or specific functionality at our discretion.

Open World Tools

During the 2015 Games Developer Conference Epic showed off to the world Unreal Engine 4's ability to render massive open worlds full of both flora and fauna. With the release of Unreal Engine 4.8 the tools used to create this demo, referred to as the Open World Tools, are now available for use in your UE4 projects.

Please note that the Open World Tools are still in an experimental state which means that you could run into bugs or stability issues while using the tools.