https://www.theverge.com/2018/8/8/17663722/facebook-ar-games-messenger-launch

Facebook’s newest Messenger feature allows users to play augmented reality games with up to six friends. It’s rolling out today with two games: Don’t Smile, which challenges users not to smile first, and Asteroids Attack, which involves navigating a spaceship.

To use them, make sure you’re on the latest version of Messenger. Then, open an existing conversation or find who you’d like to chat with, and tap the video icon on the upper right corner of the screen. Tap the star button, and select one of the AR games. The person or group you are video chatting with will get a notification indicating it’s game time. If they accept, everyone will be put into a live video group chat where the game will start with the cameras pointed at everyone’s faces.