A free program for Android, by AgonX.

What is Fortnite 3D?

You are playing as a member of the military, and your objective is to survive and destroy as many enemy forces as you can. You can do this by building and fortifying your base, exploring the world, and killing any enemy you encounter. You can use a variety of weapons to accomplish your missions.

Hence this app, lets you explore skins and builds as you see fit. You can choose to construct a base or explore the world. The world is not static, and you can change its appearance by editing the map and adding or removing objects. Plus, you will be updated on upcoming updates through videos.