Fortnite is a Third Person PVE Online Shooter in development by Epic Games, developers of the Unreal game engine as well as Unreal Tournament. The game can be played now in early access, but that's not what I'm covering now.
As suggested by my little brother, I'm looking at the Free-to-play Battle Royale stress test mode. In this game mode 100 players fly over a large map in a school bus. As players pass overhead they jump out of the bus and skydive towards buildings to loot them for guns. From the moment you jump, it's free for all; Grab a gun, some ammo, a shield potion, and a band-aid, then run your ass off to the center of the map so you don't get killed by the play area shrinking. if you're lucky, you'll kill a guy or two before you inevitably get shot in the back. Then you go to the main menu and jump into another lobby.
What sets this game apart from PUBG is a cartoony art style, a more competent engine, and most importantly: a structure building mode. Every player has a huge pickaxe permanently bound to the 1 key, and by using it to attack walls and props you can gather resources. You can then spend these resources to quickly erect new structures, one wall at a time. This is most commonly used to build walls between yourself and an attacker.
And that's it. That's the whole game. Doesn't leave a whole lot to cover. 10 weapons, 2 health types, 4 shield types, and a handful of building parts the player can build. You can also spend cash on cosmetics if that tickles your fancy, but the free models work fine for me, and even look pretty damn good.
Honestly, this whole Battle Royal genre doesn't really do it for me. I'd rather play Planetside for mass scale war games. I give Fortnite: Battle Royal a 6 out 10. It would be a 5, but I really dig the art style and I'm looking forward to the PVE mode.