Fortnite finally released in Early Access mode on PC, PlayStation 4 and Xbox One in late July. According to Epic Games, the cooperative sandbox survival game reached over a million players in its first month, making it an instant success.

However, we didn't realize this was on its way to become Epic's most successful game ever by the end of 2017. Tim Sweeney confirmed this in an interview with GamesBeat.

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It’s on track to be Epic’s most successful game ever by the end of the year. Several times more users than we expected came in. We had to really scramble to keep the servers running at that scale. It was great experience. This is just the very beginning. We have a bunch more game modes coming, which should be interesting and innovative. The whole aspect of building in Fortnite creates a really different dynamic compared to most games. Building structures, defending them, you can imagine all the multiplayer implications. We’re very happy with the transition we’ve been making, from being a lone developer who works with a publisher and puts games on retail store shelves to running our games live as services where we can constantly improve the game based on feedback. It’s been a great step. Fortnite is getting better every week.

That said, Sweeney also noted that Fortnite was much more expensive to make than the first Gears of War game, for instance. The rising costs of AAA game development steered Epic towards a different market.

Much more expensive. What we saw over the last generation — the economics started out incredibly attractive. The first Gears of War game cost about $12 million for Epic to make and earned us more than $100 million. But by the end of that generation, the costs had blown up to almost equal the profit a game could make. At this point, in this generation, I don’t know how you make a game at the triple-A level unless you sell 12 million copies or more. The teams are hundreds of people, sometimes more than 1,000. Budgets are more than $100 million, sometimes several hundred million. The scale of sales needed to justify that is crazy. We need to be constantly exploring business models that work. As the industry evolves, business models change. Epic’s survived through a number of different ones over our history, from shareware to PC retail to big-budget triple-A console and back to indie, publishing our own games for ourselves. You have to constantly change the rules.

Sweeney, who also praised Ninja Theory's Hellblade as one of the best-looking games ever created (and rightly so), then said that there is a lull in VR technology right now and the technology will need to be miniaturized to go more towards glasses than a helmet before it becomes popular.

As to Fortnite, it recently received an update adding the new Survive the Storm mode. You may read the full patch notes on the official website.