Sean Murray does not like talking to the press. He says this several times when we meet at the Guildford offices of Hello Games, the development studio he founded in 2008 with Grant Duncan, Ryan Doyle and David Ream. He is loquacious, but nervous. No one at the studio has spoken to any journalists for nearly two years, since the release of Murray’s pet project No Man’s Sky, an extraordinarily ambitious space exploration game that aimed to put an infinite universe on a games console – a game that, when it didn’t meet some players’ high expectations, triggered an appalling internet harassment campaign that left the small studio and its staff reeling.

It is hard to blame him for his hesitance. Talking to the press is partly what led to Murray’s ordeal in the first place. As the visible creative lead of No Man’s Sky, the person who talked up the science-fiction game and its enormous ambitions in interviews before it was released, he bore much of the ire when features promised during development were not present when the game came out. One poster on Reddit drew up a list of everything Murray had said in interviews about No Man’s Sky, cross-referenced with what was actually in the game. It was not flattering.

The press didn’t attack Hello Games when No Man’s Sky turned out to be a different game than the one some players had expected. Most reviews noted its emptiness, but critics also praised its lonely mood, Asimovian aesthetic, and the astounding technical feat of generating an entire universe of planets and systems complete with procedural flora and fauna. But unwittingly, the press gave the attackers ammunition. After a couple of weeks, disappointed players moved on, and the angry ones were all that were left.

“The internet is really good at knowing when somebody has made a mistake,” says Murray. “It’s not necessarily the best at determining the most appropriate response, but it’s really good at knowing when somebody has messed something up. We definitely messed up a whole bunch of communication. I’ve never liked talking to the press. I didn’t enjoy it when I had to do it, and when I did it, I was naive and overly excited about my game. There are a lot of things around launch that I regret, or that I would do differently.”

He is reluctant to relive the particulars of what happened in the weeks and months following No Man’s Sky’s release in August 2016 (“I find it really personal, and I don’t have any advice for dealing with it,” he says), but it involved death threats, bomb threats sent to the studio and harassment of people who worked at Hello Games on a frightening scale. They were in regular contact with Scotland Yard and the Metropolitan police. “We didn’t talk about it, but it was as bad as things can get, basically,” Murray says. “There’s a smorgasbord of things that the angry mob can do. It is a crowdsourced thing of how bad you can make someone’s life.

“I remember getting a death threat about the fact that there were butterflies in our original trailer, and you could see them as you walked past them, but there weren’t any butterflies in the launch game. I remember thinking to myself: ‘Maybe when you’re sending a death threat about butterflies in a game, you might be the bad guy.’”

Instead of giving up and disappearing off the map, Murray and the studio decided to double down on No Man’s Sky, keep working on it, and concentrate on what the people who were actually playing it wanted, rather than the people who were furious about it. “We did something that I think I’ve always done, when I look back at my life,” says Murray. “When I’ve dealt with shitty situations when I was kid, moving between lots of schools, or when I’ve had shitty bosses later in life … I basically just get my head down, and I work, and I avoid. I just focus on making games, making cool creative things, and that’s an outlet for me. I think the team just wanted to do that.”

Tonally, No Man’s Sky is more 2001: A Space Odyssey than Star Wars; aesthetically it is inspired by the covers of 1980s sci-fi novels. It is still recognisable as the lonely, abstractly beautiful space-exploration game I played in 2016, but three big updates have added a lot more. It is now definitely a better game, with much more to do and a clearer structure. You could always fly around the universe, explore planets, craft equipment to make survival easier, trade with aliens, and answer the call of a mysterious galactic intelligence, the Atlas. Now you can also construct bases, drive around in vehicles and – as of next week – invite other players to explore with you, in groups of four. You can crew a freighter together, or colonise a planet with ever-expanding constructions.

Multiplayer is one of the features fans have been waiting for. “A very light multiplayer was envisioned for launch, and we fought right up until the end to add it, but it was immensely challenging and we knew it was something that only a handful of people would experience due to the size of the universe,” Murray explains. “We later added a version of it for the Atlas Rises update, and it was nice, but not hugely impactful to people’s enjoyment. What players really wanted was the kind of multiplayer we are adding now.”

The update, called No Man Sky NEXT, doesn’t betray the spirit of the game. It is still meditative and calm, and hazards come in the form of toxic rain or freezing planetary conditions rather than hostile aliens or other players. There is nothing to shoot, nothing to conquer. You are still a tiny speck in an infinite universe – it’s just that now, you have some company. It is possible for players to attack each other or dogfight in space, but the game is designed for cooperation. Murray describes it as a “Star Trek away team vibe”.

“No Man’s Sky was what we wanted it to be when it launched,” he maintains. “We always talked about the feeling of landing on a planet that no one had been on before … It was lonely. It had nice calm ambient moments in it. But we always wanted to expand it. If you played [the original game] for 20 hours, you probably got the experience that we wanted. But you probably would have never picked up No Man’s Sky again.”

No Man’s Sky began life as some lines of code on Murray’s computer; he worked alone for a year on a tech demo that could procedurally generate planets and galaxies, before three more people - Innes McKendrick, Grant Duncan, and David Ream - joined him to turn it into a game. Over the five years of its development, from 2011 to 2016, the average team size was six – less than a 10th of the number of people who usually work on a game of this scale.

“I’m super proud of the guys for doing that,” says Murray. “There was a lot we got right. They made a cool, innovative, weird, ambitious game, something interesting and different in an industry where that doesn’t happen very much. They delivered on something no one else had done before. It’s a game that doesn’t really have classic compulsion loops or anything like that. It’s relaxing, therapeutic, meditative. It’s a chill game. You don’t hear people say they’re addicted to No Man’s Sky. But people do play it for a long time.”

Despite the controversy, No Man’s Sky sold extremely well, and plenty of its players have stuck by it. A year after release, when Hello Games released the Atlas Rises update, about a million people showed up to play, and the average playtime was 45 hours. The studio may not have talked to press, but it has created plenty of things for its community including elaborate online treasure-hunts and alternate-reality games. The reaction to the trailer for No Man’s Sky NEXT, says Murray, felt like a milestone.

“That’s what you make games for,” he says. “You’re stood there, and there is admittedly an angry mob in front of you, but behind that there’s a crowd of others. I just want to communicate with them directly. I want to make things for them.”

Hello Games’ mistake in 2016 wasn’t making a bad game; it was failing to manage expectations when the hype started getting out of control. But in spending the last two years working to make it the best it can be, the studio is doing right by the people who jumped aboard at the start, and stuck with the game on its journey from underdog to one of the most-anticipated games in the world to underdog again. It’s an unprecedented development story, and it put the people working on it through immense strain.

“In the lead up to launch, oh my god, I would have chopped off my own arm to have more time,” says Murray. “We were under enormous pressure from the community and external forces. We were out of money. We were working so hard, way too hard. We’ve gotten much better balance in our lives now.

“[But] if we hadn’t released No Man’s Sky when we had, and I was sat down talking to you now after we delayed it for two years, we would not have a game as good as it is right now. Now and then you’ll see a comment thread where somebody will say: ‘It’s my favourite game of all time.’ That’s fantastic. I never expected to work on something that would have people saying that about it.”

• No Man’s Sky NEXT is available on 24 July for Xbox One, and as a free update on PlayStation 4 and PC.