While it’s turned on, it automatically keeps users from installing apps unless they come from “authorized sources” — namely, Google and Samsung’s app stores. Epic claims there’s no process for any rival store to become “authorized.

Video game maker Epic Games sued Google and Samsung on Monday, accusing the tech companies of coordinating to block third-party competition in application distribution on Samsung devices.

Some users may know that Epic Games, the developer of Fortnite, has had its own app store for a while now, the Epic Games Store. The company also won an antitrust lawsuit against Google last December that found Google held an illegal monopoly on app distribution and in-app billing services for Android devices.