If you've watched HBO's Silicon Valley, you know about pivots in app development. This gamble usually doesn't turn out well, but the battle royale game mode of Fortnite is quickly becoming a textbook example in how to nail the concept. With this free-to-play spectacle in its arsenal, the game is leapfrogging even over PlayerUnknown's Battlegrounds (aka PUBG), which itself is surpassing stalwarts like DOTA 2 and Overwatch. Numbers: Last month, Epic recorded 3.4 million people playing Fornite at the same time. Just a few days ago, hip-hop artist Drake popped into a Twitch stream of the game, and it exploded into 630,000 viewers. The service's previous viewer record? 388,000.

So it's kind of a phenomenon. Basically, Fortnite is moving at Ludicrous Speed. Epic's biggest problem with the game has rapidly morphed from "How do we turn a profit on this?" to "How many acres of server farms can we get like yesterday?" What Fortnite used to be is all but irrelevant now. What matters now is the force of nature that it has become.

And, clearly not a group to shy away from a challenge, Epic has upped its own ante by cracking open a limited "invite event" for the iOS version. That's right, Fortnite is landing on iPhones and iPads as we speak... and one of those belongs to us. Does Fornite even work with a touchscreen? Do phones and tablets have enough horsepower to do this justice? So many questions. Let's dive in and try to answer them.

That Old Adrenaline

If you've never played Fortnite or PUBG before, here's the nickel tour: You start out in a plane that's approaching the center of an island, and you can choose when to hop out. Since the available play area progressively shrinks, you don't want to stay out on the fringes for too long; you'll take damage for every second that you stand outside of the designated space. But if you want to drop in closer to the center, that takes more time, and there will be a higher concentration of opponents who, like you, will be quickly scrounging for weapons, ammo, bandages, and crafting materials. So the tension starts mounting as soon as you hit the ground. Death can come quickly, and there are no respawns. Battle royale is a "last man standing" type deal.

The game gives you a number of cues to find and fix your enemy. You can hear footsteps and detect their general direction. Those are the white curving lines that pulse around the center of your screen. If there's nearby gunfire, the lines are orange instead of red. They are a bit hard to see on the 5.5-inch screen of an iPhone 8+, so folks used to playing on big TVs will need some adjustment -- or they could swap to an iPad of recent vintage.

SEE: How to play Fortnite Mobile and win: A Battle Royale guide for beginners

Either way, you can be camped in a safe-ish spot and listen to various gunfights happening around you, and people scrambling around looking for things, which is delightfully nerve-wracking (and benefits greatly from playing with headphones or earbuds). Add to this the fact that no spot is truly safe, mostly because the houses, shacks, barns, and other buildings dotting the land are in various states of disrepair. So you might look up at the ceiling of a store and discover open sky instead, with someone on the second floor about to pop a cap in you.

As long as you crouch-run, no one will hear you, and it makes you a smaller target. But it comes at the cost of slower movement, and it takes two taps to go from crouching to jumping. If the area of play is about to shrink, and you're a ways out from getting into safe territory, you might have to make a risky break for it. Other times, you can sneak right up on someone who's not minding their noise level and blast them to pieces, which never gets old and may make me a bad person.

But...Mobile?

According to Epic Games, the mobile version of Fortnite is essentially the same version that you will find on PC and consoles (aside from doing everything on a touchscreen); it has the same content as the previously released versions, and it will get their future updates. In fact, if you play the game on multiple platforms, you can link those different accounts together to sync your progress in the game. If that's not enough, cross-play is available between mobile and PC/console, but you must opt in. As a rule, mobile players will not be dropped in with PC/console players unless they enable the feature.

So that's all good. However, you're probably wondering how that touch screen works, and how smoothly the game plays. Well, we didn't experience any weird glitches or slow performance, but the iPhone 8+ is also one of the zippiest phones on the market. We encountered the occasional lag spike (the game hitching as the game server on the other end catches up to your movement inputs), but nothing out of the ordinary.

On the other hand, there's a legit learning curve when adapting to the on-screen controls. They aren't bad, it's just a bit awkward to control a 3rd-person character in a 3D environment that requires precision aiming and quick visual scanning to survive. Aiming while moving is particularly tricky. On the bright side, everyone else is dealing with these controls, too, so the playing field is relatively level.

According to the official FAQ, support for Bluetooth gamepads is "coming later." Epic did not have a more specific time frame for us when we inquired for this article. In the meantime, a tablet will give your fingers more space to work with, and your digits will obstruct less of your view. So that would be our go-to suggestion for now. iPads also have headphone jacks. *Cough*.

Fortnite for iOS does not have a release date yet, or even a release window. We don't yet know if the Android version will launch alongside iOS or come out in a staggered release. But we can tell you that the iOS version feels very polished right now, despite our experience with the touch-screen controls. It doesn't feel like a game that's still months away from a retail release. We'll keep our ears to the ground and let you know as soon as we do.

Tom is the senior editor covering Windows at Download.com.