Limbo toys with horror themes throughout, but it is in that genre that exacting sound design is essential in eliciting player emotion and getting inside the player's head.

One series praised for its ability to do this is Dead Space. J White -- a LucasArts veteran who served as sound design lead at Visceral Games on Dead Space 2 -- took great pride in the team's ability to do just that.

"During the course of production, there were meetings I would have with people -- they'd come in and have never seen [the section] before. We'd be playing, and they would literally jump in their chair. It genuinely frightened people. It might be kind of mean on my part, but I took a lot of pleasure in that," said White, when discussing the effects of the sound in Dead Space 2.

Much effort was put into thinking about how they could use the game's audio elements to enter the player's mind, sometimes without them even noticing it.

"A fundamental thing that people cannot help but respond to is the sound of the human voice and, even more specifically, the sound of human suffering. It's just an unavoidable, deep reaction that people have. So one of the elements that we'll use as part of our soundscapes are the sounds of people in misery. It may be deeply buried, but the human ear and human mind are so attuned to human vocalizations that they'll respond to it even if it's just a sub-audible aspect of the overall sound design."

This sentiment applies to smaller games -- even iOS games -- in the same way it does to triple-A releases. One Single Life on iOS, which literally gives the player's character a single life to jump from a series of rooftops to another, is one such example. Thom Kellar, Freshtone Games' sound designer, wanted to give players the sense that they were actually on that roof, preparing to jump.

"I wanted to use a lot of sounds that would make you feel a bit on edge, so there was wind and a lot of noises you'd hear on a rooftop like birds fluttering and planes flying overhead," he said. "But it kept coming back to 'What did that make me feel?' and it might have been the best or coolest or most wonderful sound, but if it's not contributing to the emotion or atmosphere of the game, unfortunately it had to go into the basket."

Manipulation

"Manipulation" can be a dirty word, and is generally used to call out poor attempts by developers to force emotions or reactions from the player. But the reality is, that audio designers try to use their craft to manipulate players in new and different ways as an enhancement.

Many games will use a rousing score to heighten the emotional state of a moment, and while music certainly has its place, it doesn't have to be the crutch used for affecting sound design games.

"We experimented early on with putting dramatic music over the top, but we felt that emotionally, it was a lot more effective to only have that big score happening towards the end when players were getting to the very edge, and they'd established themselves in the world already," said Kellar -- despite one of his initial roles being to write music for the game.

As a result, One Single Life's efficient and selective use of music gives it an extra sense of tension. Likewise, Andersen went for a similar feel with Limbo.

"[Jensen and I] rarely like music as an instrument to manipulate the emotions of the player, or manipulate anything really. We both feel that everything should be open to interpretation, and people should be allowed to project their own feelings and emotions into the experience," he said. "When you allow for that space, and at the same time create something that's captivating and immerses the player, it lets them let go of those feelings and emotions. So if they're scared it will probably make them more scared when there's no music to take them by the hand and tell them how to feel."

Of course a game like Limbo is aesthetically such that this is possible. Conversely, Uncharted or Mass Effect would be less likely to convey emotional and energetic peaks without the use of music, as it's such an integral part of the style of the cinematic experiences they're trying to create.

Of course, that doesn't mean that there's no music at all in Limbo, it's just more abstract, like Andersen's own music. "It's the personal interpretation of this boy and his journey through limbo, and instead of playing the action and emphasizing what's already there, we're trying to add another dimension... For me, it's really melancholy that this boy has been subjected to all this violence. It's just the idea that he's been habituated to it, and there's a kind of forgiveness in the music," he said. But it's also used to help juxtapose actions and emotions, such as "when you come across the Gatling guns for the first time, there's this divine music in the background, but if you add something like action music, it becomes so one-dimensional."