Death Stranding: Mads Mikkelsen explains how he came to star in the year's strangest game

A confessed non-gamer tells The Independent he was won round with grand storyboards and even grander ideas

Mads Mikkelsen doesn't know exactly what Death Stranding is, either. He might be one of its stars – one of the many haunting, real life characters who guide you through its dystopian wilderness – but he views it with the same kind of mystified wonder that has greeted the release of the game.

"I think the only one who knew exactly how this will play out is Hideo Kojima," he says, referring to the game's lauded creator. "Everything was inside of his enormous brain."

Death Stranding was released last week to almost universally positive – but bewildered – reviews, which praised its depth and innovation but wondered what it actually was. Its central premise is that the player walks around a dystopian landscape, delivering packages and connecting up cities, but that is just the gameplay around which a vast narrative about connection and society are woven.

Mikkelsen might have starred in the game but it arrived with the same sense of mystery to him, and he describes his process of discovery of being similar to the one that players will eventually have when they actually start playing it.

It is just as difficult to describe Mikkelsen's character, Cliff – at least while avoiding spoilers. He is its villain, in traditional movie terms; its big boss, in gaming terms. But Death Stranding has little concern for traditional terms, and the Danish actor and inveterate baddy is clear that the game is not about "good people and bad people".

Probably the most concrete and useful picture of Mikkelsen's Cliff is the one that revealed itself in the game's long and teasing trailers: a military man rising out of the sludge, covered in dark mystery and flanked by soldiers with skulls for faces, attached to him by glowing cords.

For all this powerful mystery, Mikkelsen's relationship with the game and with creator Hideo Kojima began on video chat. The two had been introduced by a mutual friend and collaborator, Nicolas Winding Refn – and though Kojima may be a legend among gamers, Mikkelsen confesses that he did not really know who he was, and had to be filled in by his son.

"The first impression I had of him was when I had a Skype with him." Japanese Kojima understands "everything you say in English", says Mikkelsen, but the two spoke through a translator. And though Kojima could reveal very little about that game, his enthusiasm meant that Mikkelsen was interested straight away. That led to a real life meeting at Kojima's studio, where he demonstrated more of how the game would work and look, with a huge storyboard.

"I am a big, enormous fan of comic books – and I was watching a fantastic, beautiful, interactive graphic novel," Mikkelsen tells The Independent. The two would go on to become charming friends, with pictures of the pair regularly popping up on Kojima's Twitter account.

But not everything about Death Stranding was clear straight away in those early storyboards and first conversations. In such a vast game and such a vast world, it would be hard for it to be. "The whole idea of the concept came sneaking in upon us later on," he says.

Though it might have arrived stealthily, it clearly did so convincingly too: Mikkelsen is gushing as he describes the way that one player can leave behind buildings or items that could help out another person across the world. "The idea of connecting people – not only in the game, which is an essential thing – but as a player. You can have an impact on a player in Venezuela. You might even be able to aid somebody, even tough you may never meet that person."

There's an obvious political implication to all the talk about connection and dystopia. Kojima hasn't shied away from it, suggesting that the game explores and interrogates the same societal problems that gave rise to Trump and Brexit. But Mikkelsen is anxious not to be limited by those issues.

"Not everything is about Brexit or Trump," he says, when pushed about the societal relevance of the game. "That's to simplify the world of Hideo."

The game is about something deeper and more timeless than just a political response, he says. "You could have made this point during the Second World War or the First World War You might have been able to do it during the fall of the Roman Empire."

To focus so much on the immediate political meaning is dull, if nothing else. "It becomes boring," he says. "You can always make a film that's very direct. I think the world is bigger than that; it's much more complicated than that."

That approach is wrapped into his acting, too. If he spent all of his time "the character will disappear and I will just be a mouthpiece for whatever agenda" he cautions.

As they got to the actual work of that acting, Mikkelsen acquainted himself with the strange work of acting in a video game for the first ever time. Though he has acted in a grand, CGI-powered movies like Doctor Strange, he describes the work as being more akin to the indie, emotive films he has worked on in Denmark – but with invisible props.

At the beginning, a camera is placed onto a helmet, and the helmet is placed on your head. The camera is watching for motion tracking rather than filming you, which means putting on a strange outfit to allow it to watch properly. "You come in the morning and you have a makeup artist put dots on your face then they slick your hair back and put on the helmet and the green suit," says Mikkelsen.

"You look like... I don't know what you look like. Luckily there were other actors who look the same. So you feel at least half normal."

Then the actors headed off to the storyboard – a vast sketch "full of cartoons and drawings, like a graphic novel", says Mikkelsen. "He would tell us approximately: this is taking place in this kind of a background. And then later on when we came back and started working on something new we would talk about something specific in this scene."

That left plenty of space to play with the ideas of the game, says Mikkelsen. Despite the technical constraints of having your face captured digitally, the actors could still range around.

"There was quite a bit of freedom," with Kojima leaving space to improvise, says Mikkelsen. "He was very open for us to come with ideas to make it more intense, more emotional; other words, other gestures."

The process he describes is something like a game – something like this game, specifically. Mikkelsen describes a process in which you have a start point and end point, as well as some locations you need to hit on the way, but that it was up to the actors how they navigated around those. "He was working very much like that." (That just happens to be exactly how Death Stranding works, too, giving you locations to deliver to and asking you to find your way between them.)

The improvisatory relationship between the pair even led to tweaks to the character. Kojima has said that it was seeing Mikkelsen smoking during a break in filming that led to his character smoking, too – now a clear and identifiable part of the character, but one that grew out of their friendship.

Armed with ideas from the storyboard – and an indication of what the game might look like when the green screen behind you is filled in – actors got down to acting. And the machinery quickly faded into the background, Mikkelsen says, until it didn't.

"It was just becoming part of us. We kind of forgot it – until we'd bump into stuff. You would always bump into things, mainly because you forgot you're wearing it."

Other objects wouldn't be there at all. "You might not be carrying the real prop, because it always had to be a green thing, so you could paint in the things you wanted – but that's were our imagination comes into play", he says.

One might presume that actors would be used to this from wildly CGI films such as Doctor Strange, but Mikkelsen notes that in those cases "you're still wearing your costume, there's still some kind of set, some kind of props that are the real thing". The action sequences are actually notably real; if the story called for characters running across the ceiling, then they really did so, strapped up with wires. When making Death Stranding, basically nothing was real; those wires were replaced with computer cables and actors had to envision the rest.

Imagining yourself into a post-apocalyptic world filled with floating death-monsters might seem a lot of work, but there were things to hold onto. There was something recognisable in all of the strange scenes he said. Even if "some character are more extreme than others, there's a certain humanity in all of them", he says. That meant that you might not know precisely where the scene fits in, but "you could still dive into it and say 'I know what this is about'".

Now Mikkelsen is looking forward to finding out what the rest is about, too. Through making Death Stranding, he says he underwent something of the same experience that the player will go through. "I got smarter – I knew more and more. The game kind of revealed itself to me." Plenty remains mysterious, though: "I'm only in bits and parts of it. So there's an entire 50 other worlds that I'm not part of".

He has still only played a short amount of the game, and needs someone to help him out as he does so; a real analogue to those virtual players who can help each other out across the world, over the internet, within the game.

"I've played for an hour and a half or two hours," he says. "I'm still one of these guys who will look down at the remote thing. I had somebody help me – will ask them, 'what's around that hill?'" When the game is out he hopes to sit down with his son – the real gamer of the family – and play through it together.

But the astonishing experience of that brief time playing the game is clear. "I was blown away," he says. "It was mesmerising."