Papa Sangre II doesn't try to wow you with its graphics — it doesn't even have any. It's an audio-only experience for iOS, and the sequel to perhaps the scariest game I've ever played. In it, you navigate a dark and treacherous world using sound alone, guided by an unreliable narrator voiced by Lord of the Rings and Game of Thrones star Sean Bean. By removing the visual component, the game strips out one of the biggest selling points for games, yet doesn't feel any lesser for it. "The fundamental thing that we love about these games," says Paul Bennun, CCO of developer Somethin' Else, "is the fact that the graphics card in your head is way better than anything you can get on any computing device."

The first thing you're told in Papa Sangre II is that you're dead. And the only way to get back to the land of the living, it seems, is to navigate a world of darkness and venture through the memories of the deceased. Doing this is surprisingly intuitive, even though you can't see a thing. In order to move forward, you tap the two lower corners of your iPhone or iPad to simulate walking. When it comes to figuring out where you need to go, you simply listen — the game uses binaural audio so that you can hear where things are. If you're surrounded by pools of poisonous water, for instance, you know you're safe if the sound is coming from the left or right; if it's directly in front of you, you'll end up walking right into it. Much of the game involves following a particular sound in order to grab an object or reach an exit while avoiding other noises that will harm you.

This was all true of the original Papa Sangre, but the sequel adds a few key features that make it feel much more like a complete game, as opposed to a really cool tech demo. For one thing, you can now use your in-game hands by tapping the top of the screen. This is useful for opening doors, clapping to scare away monsters, or even firing a gun during some surprisingly engaging shooting sequences. It makes you feel a little more in control, since you don't always just run away from danger. "We always wanted to have a more rounded way of interacting with the world of Papa Sangre," Bennun says of the addition.

But perhaps even more important are the new gyroscopic controls that let you physically turn toward or away from sounds. It adds a whole new level of immersion — I found myself playing by standing up, eyes closed, headphones in, and actually walking around in circles trying to find my way around. There are other control options that let you manipulate the screen to move around, but none offer the intuitiveness or immersion of the motion controls. "It's sort of like Oculus Rift for your ears," jokes Bennun.

This would all be for naught if it the game wasn't fun to play, but the team at Somethin' Else has shown a surprising amount of creativity. It's amazing how many things you can do and places you can go even when you're shrouded in darkness — Papa Sangre II takes you everywhere from a burning building to a submerged submarine, with each level feeling distinct and engaging. A lot of this has to do with the terrific sound design — the studio built its own 3D audio engine for the game, appropriately called Papa Engine — though Bean's performance does a lot of heavy lifting as well.

Bean plays your tour guide through the underworld, a character he describes as "a chaperone in a spooky environment." It's the kind of narrator who you can never quite trust. "You don't know if he's your friend, if he's trying to help you, or if he's trying to lead you into a trap or into danger," Bean explains. "It was a neutral, unbiased, impartial kind of voice, so it was up to the player try to figure out whether I was their friend or not." Bean's gruff performance does the job admirably. And even though you don't know whether to believe a thing he says, his voice is always in your ear and one of the few comforting sounds you'll hear.

This wasn't the studio's first brush with celebrity. Last year Somethin' Else released another audio game, The Nightjar, which featured the voice of Sherlock star Benedict Cumberbatch. In both cases, working with a seasoned professional really helped make the experience better, especially when the narration is such a huge part of the game. "Getting an actor who is both very, very good with the words on the page, but also has a wide variety of emotion that they can communicate that isn't standard Hollywood, was very important," says Bennun. "So that's why we ended up with Sean Bean."

It didn't take much convincing, according to both parties, though actually explaining what the game was and how it worked proved a bit challenging. "It's very hard to imagine what it's all about," says Bean. That was true even after he had read the script and talked to the game's producer. It wasn't until he actually played the game that he understood. "Because it's something purely audio, it's much more scary, and there's much more tension," he says. "It's terrifying having a go at it." The final result is a game that's as spooky as it is playful, an experience that's brimming with inventive ways to use the audio-focused format. It's not nearly as scary as the original game, but it builds on that premise to create a much bigger and deeper experience. And it might not be the last we hear of Papa Sangre, either.

"We're certainly not short on ideas," says Bennun.