Pre-Registration (Google Play) is Google Play's pre-launch sign-up: users register for an upcoming app or game on its store listing, then get notified on launch day, with eligible devices installing it automatically.
To open pre-registration, a developer uploads an app bundle to define supported devices, chooses countries and starts the campaign in Play Console; users then pre-register from the store listing. At launch, pre-registered users get a push notification from Google Play, and eligible devices install the app automatically: apps up to 200MB over Wi-Fi or mobile data, up to 2GB over Wi-Fi only, and nothing larger. A campaign can last at most 90 days from when it first opens in a country. Apple's nearest equivalent is the App Store pre-order, which also downloads the app automatically on release.
The ASO value concentrates on launch day. Pre-registrants can turn into a burst of installs at release, the kind of install velocity store algorithms tend to reward, and the listing gets a live audience to refine messaging on before it matters most. Teams can attach a one-time pre-registration reward, show pre-registration visitors a custom store listing and buy sign-ups through Google Ads App campaigns for pre-registration. Two cautions: a pre-registration is intent, not an install, and missing the 90-day launch deadline ends the campaign in every country, so fix the launch date before opening it.
Example
A strategy game opens pre-registration in five countries eight weeks before launch, promotes the listing through its community and an App campaign for pre-registration, and offers an in-game starter pack as the reward. On launch day, eligible devices install it automatically.