Start a new conversation in iMessage. Now tap the app icon next to the text box. Tap the App Store icon in the apps menu to open the store and see a collection of apps, games, and stickers that you can try in iMessage on iOS 14. After the cap, you can tap your chosen game and click the Get button. To install it just like with any other iOS app. Once you've downloaded a game or app of your choice, you can start using it by tapping its icon at the bottom of the message box.