Epic Games Inc. expanded its antitrust legal fight with Alphabet Inc.’s Google by accusing the tech giant of conspiring with Samsung Electronics Co. to block rival app marketplaces through default settings on mobile devices sold all over the world.

As a federal judge weighs what corrective steps Google must take to remove barriers surrounding its Play Store, Cary’s Epic Games has accused the internet search giant of finding a new unlawful way to protect its Android app store monopoly.