Fortnite: Battle Royale might look a lot like Player Unknown's Battlegrounds in a whole lot of ways. It's those differences that coule make it interesting in ways strategic: the biggest difference between the two is Fortnite's building pathway, something largely cribbed from the game's base-building roots. You start the game with a pickaxe, which you could use to collect resources from buildings, trees and the like. You could use those resources to build walls, stairs, and platforms. In my experience, the quick movement and unpredictability of the game make the base building more of a lark than anything else, even if you do see it well-deployed every once in a while, and even if it did become much grander in the limited time 50 vs. 50 mode. There is one emerging strategy, however, that makes an interesting use of the system for what appears to be one of the more reliable strategies for winning the game.
The technique has been dubbed the "stairway to heaven," which offers up a pretty big clue about how it works. People have been using it since shortly after Epic released the game mode, and you could see a ton of videos across the Internet. Essentially, you start the game by landing in an area with a ton of trees and other resources and get mining as quickly as possible, grabbing some bandages and weapons along the way. You'll then get towards the outer edges of the safe zone and then just start building up as high as you can go, until you're so far above the rest of the game that no other player is likely to notice you hanging out up there in the sky. Then you just start building a plank towards the center of the safe zone, which shouldn't be all that hard to do for most of the game. At the end you may have to shoot a single other player, but the height advantage should really help here. If you're lucky, however, you might be able to win without firing a shot if things get messy down on the ground.
More ambitious/lucky players might do this strategy closer to the beginning of the match if they manage to grab what they need in short order, while others might use it more as a mid-to-late game technique once they've already got a decent sniper rifle or a ton of building materials. The basic concept is the same, however. Here's a decent tutorial video:
The strategy is not unbeatable: people could shoot you down if they look up -- rocket launchers, in particular, could make short work of your structure. You also might well run into someone else up there and have to shoot it out at the top of the world. You also just might find the technique a little difficult to execute for one reason or another and wind up plummeting to your death or running out of resources. Still, it seems to take out some of the that the game could have on the ground, and it's certainly a different style of play.
It's a good example of some of the emergent gameplay we've started to see with this wacky battle royale title: another one might be the time that people started riding teammates rockets and raining death down across the map. Epic seems committed to allowing these things to continue, as well: part of the fun of making a game with a strong freeform component like the building system is seeing just what players wind up doing with it. I'd be surprised if the developer did anything to nerf the strategy by limiting build height or anything like that, but I'd be less surprised to see it introduce some sort of weapon specifically designed to let people on the ground mess with people way up in the sky.
However the situation develops, the stairway to heaven strategy is a good example of what makes this game unique, and it makes me interested in how Fortnite will continue to grow.