PUBG Mobile goes live in the US on Android and iOS platforms
In fact, even the description of the game in the App Store and Google Play Store says that the current version does not represent the final quality of the game, as the developer plans to keep optimizing it and add new features.
In case you're wondering, this is the port of a fully fledged PC game, not just a low-quality version specifically designed for mobile phones. Considering the game major optimization issues on the PC, the mobile version works surprisingly well. On top of that, it's completely free and does not seem to include any in-app purchases.
The recommended specs for a smooth gameplay experience are Android 5.1.1 or above and at least 2GB RAM. For iOS users, it requires an iPhone 6 or above, as well as iOS 9.0 or later.