With touchscreens and motion controls, we're seeing a steady stream of incredibly creative and inventive games. Even still, an experience that almost entirely consists of audio is novel. And that's exactly what the team at Somethin' Else has created with Papa Sangre: a terrifying horror experience that is portrayed to the player solely through sound. In the iPhone game, only your ears can guide you as you explore a land covered in darkness and full of horrible monsters.

Ars spoke with Somethin' Else's Paul Bennun to learn just how hard it is to create a game made of sound.

"I've wanted to do a game using only sound for as long as I can remember," Bennun told Ars. "They say 'the pictures are better on radio,' and the team's suspicion was that we could create a world as detailed and carefully created as any console game with great art direction and game design—using sound alone. The broad ambition was for an environment as atmospheric as, say, Rapture or as smart and subtle as the Aperture Science labs."

The game drops players in the land of the dead, where they're tasked with not only staying alive, but also finding and saving lost souls. Chimes and other sounds effects help guide you along, and you need to listen closely to determine how close they are. Likewise, enemies will growl and snarl and chase you. You'll want to avoid them. Movement is controlled by the touchscreen, where you can simulate footsteps with your thumbs and turn to face the sounds. It works surprisingly well, and according to Bennun, was terribly hard to create.

Not only did the team—which consisted of a six-person core and around a dozen other contributors—have to build its own 3D audio engine, but they also had to design an experience without any visual cues. As you might expect, this wasn't easy.

"Creating a game that was 100 percent accessible to blind people was also a primary consideration for us, and this threw up some knotty issues," Bennun explained. "VoiceOver is very powerful, but as none of the development team were native users of the iPhone's accessibility functions we had a practical learning curve in how people used them, and required a special set of play-testers to assist us. In the end, VoiceOver couldn't do everything we needed, so we had to use some legal hacks and created an entirely separate game UI for VoiceOver users so they'd have fun playing the game.

"Some have called the game 'a game for blind people,' which is a totally wrong. It's a game for everyone. It's just that if we ever get around to a multiplayer version, don't play against someone that uses VoiceOver unless you do too. They'll kick your arse."

This also led to problems when it came to tuning the difficulty of the game. During play-testing some blind players managed to breeze through the game, while other players found even the opening areas very difficult. But while the development, which lasted around a year, was full of obstacles, it also allowed the team the ability to create a uniquely engrossing experience.

"We realised we had the opportunity to create what we call 'the ultimate first-person game,'" he told Ars. "The illusion provided from successful binaural audio is closer to immersive reality than anything a screen can provide. That is, when it truly works, you're actually there, getting a closer approximation to the information you'd get from a real space. So some people really find the game incredibly, unplayably, scary."

Unsurprisingly for such a singular experience, the response has been somewhat mixed. While for the most part the game has been heaped with praise, there are also some very outspoken detractors for whom the audio-focused experience simply didn't resonate.

"There is a small section of people who just don't get it, and for whom the world never comes to life," he said. "It could be because the [head related transfer functions] we are using are just too different to people's 'built-in HRTF'; it could be because they just aren't very auditory people, or it could be because they want something different from a game than what we're offering.

"These people just think what we're doing is bollocks—typically they say stuff like 'It's just pointing yourself at sounds and walking towards them,' or 'It's not 3D audio at all.' Luckily there aren't very many of them. The other negative response has been toward the facts of the product: '128MB? No graphics? Only works on a modern device? HAHAHAHAHAHAHAHAHA!' ... that kind of thing. And the launch price [$6.99]—particularly [Americans] have been fairly negative about that. That's a long and complicated story though."

And while the initial version of Papa Sangre is quite impressive, Bennun and the rest of Somethin' Else aren't resting on their laurels. A new update is in the works that will feature a "Big Field Mode," which will utilize the iPhone's GPS and gyroscopes to "map game-space onto meat-space ... go into a big field, blindfold yourself and truly get immersed running away from monsters."

There might also be some other audio games in the works that build on what was learned during the development of Papa Sangre, though there's nothing to announce right now.

"Some have likened the experience of Papa Sangre to being inside a novel," said Bennun. "So we're also exploring game worlds with stronger narratives, which is fairly exciting, and puzzles. Stay tuned!"