Pixel Heart Studios' audio-only horror game, Vanished, is available for free until Oct. 1 for iOS devices.
Vanished is set in a world "without light, with no memories of how you got there and no clues on why everything has disappeared." The game uses the iPhone's internal compass and accelerometer to recreate a person's movement. Players hold their phone in the direction they want to travel and touch the screen to walk. When in danger, they shake the phone to attack. All exploration is done with the help of audio cues; as players move, the world "rotates" and provides different sounds.
"We think that imagination is the most powerful hardware a game needs, so we tried to develop something that is build totally around it," the game's description reads. "The game itself is only part of the experience. It's your imagination that creates the world in which you play. No graphic. No images. No walls."
According to the game's site, Vanished is an experiment, but Pixel Heart hopes to expand it into something more complex.
Vanished is currently available through the iTunes App Store. After Oct. 1, the game will be available for $0.99.