Washington University computer science graduate Nathan Gitter has released Rainbrow, an eyebrow-controlled arcade game for iPhone X.

The simple game requires players to use their eyebrows to move an emoji face up and down the screen to collect stars, worth one point each, while avoiding other emoji obstacles such as cars, basketballs, and ducks.

Simply raise your eyebrows to move the emoji up, frown to move the emoji down, or make a neutral expression and the emoji stays still. Note that if you raise your eyebrows, and keep them raised, the emoji will continue to move in an upwards direction, and vice verse when maintaining a frowning expression.

While there are no levels, the game gets increasingly difficult as more obstacles appear. The goal is simply to get the highest score possible, but players can only compete against themselves right now. Gitter told us that he plans to integrate Apple's Game Center for multiplayer competition in a future update.

Rainbrow is a novel concept since it's an early example of a game using ARKit , an iOS 11 framework that can detect the position, topology, and expression of a user's face in real time using the iPhone X's new TrueDepth camera system.

Gitter told us he believes there is a lot of future potential for face-based apps, especially for those that improve accessibility. He pointed us to another face-controlled game that was released earlier this week, Nose Zone, which tasks players with destroying targets by pointing at them with their nose.

Upon first opening Rainbrow, a prompt asks for permission to access the front-facing camera. As with any app, this permission can be toggled on or off at a later time in the Settings app under Privacy > Camera.

Rainbrow's privacy policy, which all apps with face tracking are required to have , says that depth data is collected only for gameplay purposes, only stored on the device locally, and only for the duration of a game session. The policy adds that depth data is never stored remotely, given to third parties, or used for any non-gameplay purposes.

Rainbrow is free to download on the App Store for iPhone X. Gitter told us he may add an optional in-app purchase to unlock new emoji characters in the future, but he does not plan on implementing ads into the game.

Gitter works at mobile app studio SwiftKick Mobile in Austin, Texas. His personal website says he's available for iOS design and development work.

Updated: Lucky Kat Studios reached out to us after we published this article to alert us about its upcoming game Wacky Face, now available for pre-order on the App Store ahead of its December 20 launch.

Wacky Face requires players to wink or open their mouth to attack enemies. Like Rainbrow and Nose Zone, the arcade game uses both ARKit and the iPhone X's new TrueDepth camera system to capture facial depth data.