“I get so many emails from people saying they thought the game looked atrocious and they played it just to laugh at how bad it was.” Nelson Sexton has a pretty good attitude towards his game, Unturned [Steam page].

On first glance, the Fisher Price art direction of this Early Access zombie survival sandbox surely wouldn’t trouble old man DayZ and his gang. But it’s had 17.5 million downloads on Steam, with 1.25 million people playing it in the past two weeks. Players really like Unturned: its Steam ratings are 92% positive. And Sexton, its sole maker, is just 18. I was really curious who this guy is, so I rang him up. I think you might like him – and maybe Unturned, too.

Nelson Sexton lives in Calgary with his dad. He’s gently and precisely spoken, self-assured given his years, and has that cute Canadian burr. Continuing that opening quote, he said, “But then – and that’s not to say it isn’t bad, but who knows – they tried it and they actually really enjoyed it, and that they wouldn’t have tried it if it cost money.” It’s hard not to like someone who made a game played by well over a million people a fortnight and says “who knows” about whether it’s good.

Sexton started making Unturned when he was 16, so throughout its development he’s been at school, not that he really told anyone there. “I remember my chemistry teacher came up and said, ‘Hey, you made Unturned! One of my students was talking about that. Can you fix my computer?’” I see him as part of the same new wave of game makers that I wrote about yesterday, people who’ve grown up with Roblox, Minecraft and DayZ, and witnessed them being built around them as they’ve played and built in turn.

One of Unturned’s charms is that it’s so evidently personal. Its logo on Steam is displayed in white Arial, with ‘Free to play’ in yellow italics below, all against a blurry image of one of its landscapes. It’s less than sophisticated. If you’ve played Roblox, you’ll recognise the game’s visual style. Your character is a block of what looks like tofu with a pixelated smiley face. The maps are simple, sprinkled with generally untextured trees and buildings in primary colours. Shops have their trade written above them, like ‘Clothes’ or ‘Post’. It’s a toy town zombie apocalypse, and even more endearingly, its two default levels are set in Canada: colourful Prince Edward Island and snowy Yukon.

“When I was starting out I wasn’t trying to make it goofy, I was doing what I was able to do,” Sexton says. “But once I had established the style with the way the characters look, the way the environment is, I built on that. The goofy, happy, easy to get into look, I think now most of the things in the game fit into that.”

The result speaks of fun in a visual language that’s familiar to the age of Minecraft, and the environments are very readable and easy to navigate. But it also disguises genre-typical deep systems. Death might leave enormous pools of bright red blood, but it’s still swift and unforgiving. Your hunger and thirst constantly tick down, there are many items to scavenge, vehicles to drive and animals to hunt, and you can build forts and craft.

Still, the fact that Unturned is free-to-play takes a large part in its success. It’s supported by one-off payment of £3.99, which gets you a Gold account: gold clothes, special servers, extra customisation and other ephemera. It’s otherwise completely free, which has meant that friends can always play together, just like they can in Roblox. I suspect he’s a lot more canny than he likes to put across, but Sexton brushes it off as a light decision. “I guess it had to be free-to-play because it had always been free-to-play. I didn’t ever really consider selling it.”

In fact, his conviction was so strong that even Dean Hall couldn’t change his mind to sell it for $5. “I still lurk in the DayZ subreddit and I think it was a couple weeks before release I saw a post about Unturned, and Dean Hall, who made DayZ, actually posted on there. I feel so bad about this because he had a bunch of feedback and said, ‘I think what is there looks pretty promising, to be honest,’ and I included that on the store page because I was just so excited that he’d say anything about it. It was just absolutely amazing. In retrospect, this just seems such a stupid thing to do. Then, when I was doing the store page for 3.0, I clicked on the link and he’d actually deleted the comment, and I felt terrible.”

Sexton actually started out making games with GameMaker, having been introduced to it at a summer camp. He taught himself with tutorial examples that shipped with it, captured by what it was opening up: “To me it seems like drawing is a way of getting your imagination onto paper, and then computer games are a way of getting your imagination into something you can actually interact with, and I really love that.”

After a year of sharing his GameMaker projects on the web, noting their ratings and comments, Sexton graduated to Roblox, in which he made games for the next couple of years. Starting in September 2012, at 15 years old, he made Deadzone, a version of DayZ. Like everyone else at the time, he was excited by DayZ heralded. “It was unique with its atmosphere and the stressful aspects of interacting with other players. I really wanted to play it with my friends, but a lot of them didn’t have ArmA 2, and to mess around with my own ideas I had for that kind of game.”

By January 2013 Deadzone had a pretty big following; to date it’s been played over five million times. There was some controversy that it was very similar to another Roblox game, Apocalypse Rising, leading to a spat between the two games’ fans, but Sexton’s main concern was that he couldn’t improve on it easily. “It was terribly designed,” he says. So he spent a couple of months trying to make a sequel, and found that Roblox didn’t quite support all he wanted to achieve.

So in the summer of 2013 he moved to Unity to start Unturned. “It was like beginner steps into Unity, and I just assumed I could make a copy of Deadzone in Unity, but of course I had no idea of what I was doing. Not that I do now.” It was originally made for browsers so more people could play, but this first version shared Deadzone’s issue of being difficult to add new things, so he started making a second version in January 2014, which ditched the browser, and released it on Steam in July 2014, followed by version 3, the current one, a couple of months later.

From the point it was first playable, Sexton made it public so he could get feedback. It strikes me as remarkably bold for someone so inexperienced with a complex engine to have shared the game so early, but being public seems a natural part of game-making for his generation. “It would have felt weird not to put something out,” says Sexton. “If I’m working on a new feature and I haven’t asked for people’s thoughts, or showed what it looks like, it feels really weird.”

I wonder if he’s just a naturally confident person, and he is, at least about Unturned. “I spend so much time working on it, and Unturned’s community seems pretty friendly – when they talk to me. I don’t know.” He laughs. But on the other hand, for his computer science class he worked on a project that he wasn’t ready at all to show off. “It was very scary to be doing that. With Unturned it’s very natural to be putting it out and showing it to everybody, but showing this to my class was absolutely terrifying. Actually, during the presentation, I clicked one of the wrong buttons and my demo ended up not working, so that was horrifying.”

Until a few weeks ago, Unturned has enjoyed daily updates, continuing the tradition Sexton set from its first release. He’s watched Valve talks, where they argue for big updates with a story and lots of new content, but it isn’t for him. “I interpret the intention of Early Access to be trying to take feedback from as many people as possible, so iterating quickly seems to work well, because people can see their feedback quickly and they can decide if it changes their opinion.”

But with hundreds of servers active today, server owners found having daily updates hard going, so they asked him to slow down and now Sexton updates on Fridays. It seems he’s not totally comfortable with that. “It’s been in some ways bad for the game because people are coming back every week for a bit to see what’s new,” he says. The thought of monthly updates just makes him think they might uninstall it.

Keeping the game fresh seems to be on his mind: looking long-term, Sexton would like to take Unturned to a point where players can create anything, despite the fact that its Workshop is already home to many new vehicles, guns, outfits and maps. “There are all these maps that are probably better than my default maps, and a lot of people seem to agree,” he says, happily.

In the medium term, he’ll continue improving the game, maybe finding people to work with, too, particularly if he decides to take up one of various publisher offers to put Unturned on console. The need for controller support and improving menus would then also be released on the PC version. There’s a plan, then, a sage mixture of caution and confidence. And when Unturned’s out of Early Access, maybe he’ll go to university.

I wonder what Sexton has learned about the sandbox zombie survival game over the past couple of years, and his perspective speaks volumes about how he’s inadvertently become a wrangler for all the different expectations people have for the genre. “When these games are announced, everyone’s excited because it’s, ‘Wow, we can recreate things from The Walking Dead TV show!’ And, ’It’ll be the ultimate huge base-building game!’ They end up being played by a whole bunch of different people, and they aren’t necessarily balanced for them all.”

He’s seen the same in Unturned. “PvPing is the dominant vocal group. They create servers, remove all the zombies, spawn everyone with guns, and there are mods that add a currency to buy weapons. There are other groups that are super hardcore. They want it so you can break your finger bones.” Not that your character actually has fingers. “And then there are people kind of in the middle, who want The Walking Dead experience, where you’re sneaking through the city and surviving the zombies while watching out for people and maybe teaming up, maybe killing them.

“I think to some degree some of these ideas don’t actually even work together. If you want a game that has millions of zombies in the city all at the same time, but also want easy base-building… Maybe someone will make a game that blends these things together perfectly, but…”

Maybe he’ll be the one to make it. Maybe after university, maybe sooner. But does he need to choose yet? He’s already got so much behind him, and Nelson Sexton’s got it all in front of him, too.