Facebook Messenger for iOS and Android now features instant games
Some of the famous games that can be played on Facebook Messenger include Pac-Man, Words With Friends, Space Invaders, Arkanoid, EverWing, Nex, and Galaga. The games should be available on devices running "newer iOS and Android", though Facebook doesn't specifically say what OS versions you must have.
The new Facebook Messenger games come with score-based leaderboards, single or group chats, and the ability to challenge friends. Once you're getting the latest version of the app on a supported device (either on iOS or Android), you should be able to see a game controller icon bellow your conversation window - that's where the fun begins!