The Game Developers Conference is happening in San Francisco this week, and that means Epic Games is here to try and get game devs hyped about its Unreal Engine.

It's traditionally a tech-heavy pitch, and this year is no exception: there's new support for the augmented reality Magic Leap One headset,  a big batch of free assets from Epic's soon-to-be-shuttered Paragon, a new replay system for Unreal Engine, and more.

But this year there's a colorful, cartoony elephant in the room: Fortnite. The game has become something of a phenomenon since its debut last summer, due in large part to the popularity of its F2P cross-platform Battle Royale mode. 

Last week the game broke Twitch's record for most-viewed stream, presumably because the streamer in question (Tyler "Ninja" Blevins) was playing alongside former NFL player JuJu Smith-Schuster, rapper Travis Scott, and Drake. According to founder Tim Sweeney, the unexpected success of the game is both driven by and now driving Epic's community-focused approach to game development.

"The current phenomena driving games and driving players -- it's Twitch, it's YouTube, it's these influencers, right," Sweeney tells Gamasutra. "A golden game reaches them in some unique way, and gives some of them an opportunity to shine, and they'll bring you the users."

This is not a new message, but it's one Epic is doubling down on this year as it tries to ride the Fortnite wave. As game markets grow ever more crowded, Sweeney suggests devs think hard about how they can work together with streamers and YouTubers to get a game noticed. 

"They're far more effective at [marketing your game] than the top ten list on the App Store, where the cost of entry is a hundred million dollars. Or, going through a big publisher or, trying to get into the top charts on Steam," says Sweeney. "I'd go for the influencers; that's the current phenomenon. And it is a phenomenon that's just getting started."

Both Sweeney and Epic CTO Kim Libreri acknowledge that this is a strategy probably best-suited for online multiplayer games like Fortnite or PlayerUnknown's Battlegrounds, the phenom Epic effectively replicated with Fortnite: Battle Royale. But they're quick to argue that indie devs with smaller single-player games shouldn't overlook platforms like Twitch, even though it's dominated by popular games like Fortnite and Battlegrounds.

"If you've got a game that you're putting out as a little indie developer, and it's got a little bit of magic in it, then streamer will be able to find that bit of magic," says Libreri. "You'll be able to evolve the game over time, and cater to the audience."

"It couldn't be further from the old days"

Again, this is not a new idea in the world of game dev -- but it is relatively fresh for Epic. More notably, the fact that Sweeney and Libreri can come to GDC this year and talk up Fortnite as a success thanks to rapid iteration and community engagement suggests the company's 2014 pivot to focus on open community development of free-to-play games is paying off.

"You get this direct link to the people playing your game, which we never had before," Libreri continues. "It couldn't be further from the old days, when we'd slap something in a box and then someone somewhere would play it. But now if somebody finds some magic, they can tell you, and you can adapt to it. I think that's an amazing opportunity that really levels the playing field. You can be a little tiny developer and have massive success if you make something cool."

Of course, Epic is not a little tiny developer (though Libreri is quick to point out that the team who added Battle Royale into the original Fortnite was small -- at first), and the resources it's putting into supporting and updating Fortnite are significant.

But in keeping with Epic's history as a game dev and engine maker, the work being done on Fortnite is also being rolled out to UE4 devs to use in their own projects. This includes a new replay system that Libreri hopes will be embraced by Fortnite players and streamers, as well as UE4 devs who are looking to give their fns more tools to talk about their game.

"We want all the auxiliary bits and pieces around that that allow them to harness their community," Libreri says. "So the replay system is a big part of that, you want to be able to present people in ways they've not seen before, and replay allows them to do that. "

Sweeney is also keen to get Unreal Engine developers thinking about making their game as cross-platform as possible. Last week the company launched Fortnite: Battle Royale on iOS with cross-platform support, and Epic's chief says this is key to building a big, sustainable audience for your game.

"People love to play games with their friends. We've really been trying hard to build the engine, all the systems and technologies to make that possible on a large scale," says Sweeney. "One of the big things is making it possible to build one game that runs on all platforms and inter-operates...I think that's going to be key to having these widespread social experience games."

And while Fortnite remains Epic's chief focus, he's quick to point out that everything the company is doing there is also rolling out to other teams, pointing to the recent mobile debuts of games like Rocket League, PUBG Mobile, and soon Ark: Survival Evolved.

"These are all high-end games coming to mobile devices, and I think we saw this trend starting in Korea about two years ago, when the mobile market there shifted from being primarily casual to primarily serious games," says Sweeney, who last year whipped out his phone mid-conversation to excitedly showcase the graphical fidelity of Korean mobile game Blade 2 running on UE4. "Now the far majority of playtime and revenue goes into serious [mobile] games. And I think by the end of the year here, North America and Europe, it will be same thing in the mobile market."

Pressed on this point, Sweeney says that even if you're not an Unreal Engine developer, you should be looking at cross-platform support and persistent social features if you want your game to succeed.

"We think that's going to be the overwhelming trend that reshapes the game industry over the next few years: gaming as a social phenomenon, bringing together all players across all platforms. Playing with real-world friends," says Sweeney. 

"And that's why we've been pushing this whole question of interoperability so hard. Microsoft and Sony both agreed to support cross-progression and cross-purchase with iOS, Android, PC, and Mac. So of the 36 possible combinations of platforms that could theoretically play together, there are 35 supported, and there's only one more wall that we hope will be torn down over the next few months."

As the year spreads out ahead of us, Sweeney has two pieces of advice for game devs who want it. First, if you have a multiplayer game, try to get to a point where you can do cross-platform sessions across as many platforms as possible.

"If you're building a multiplayer game, the challenge is to connect players with their real-world friends. People who play together with their real friends are far, far more dedicated to any game than people who play alone or with strangers," says Sweeney. "So anything you can do to target those folks is the way to go."

And second, whatever kind of game you're making, carve out time to get up to speed on who's streaming similar games on platforms like Twitch or YouTube. Try and get your game into their hands, and don't worry if the top broadcasters don't pick up on what you're putting down -- sometimes it's the new or niche streamers which drive your game's success.

"These streamers want a niche, right? It's probably better to be the number two streamer for a small game than to be the number 300 streamer for a game like Fortnite. And so there's going to constantly be opportunities for streamers to build an audience," says Sweeney. "And it's very complementary, right; streamers want an audience, the game developers want attention. If you look at how Ninja developed, he was maybe towards the bottom of the top 10 on PUBG. And then number one on Fortnite. Everybody wants their break, and when developers and streamers can have that break together, that's awesome."