Bethesda Softworks is suing Warner Bros. and Fallout Shelter co-developer Behaviour Interactive over the recently released Westworld, alleging that the mobile game based on HBO’s TV series is a “blatant rip-off” of Fallout Shelter.

In a suit filed in a Maryland U.S. District Court, Bethesda alleges that Westworld — developed by Behaviour and released this week for Android and iOS — “has the same or highly similar game design, art style, animations, features and other gameplay elements” as Fallout Shelter.

Fallout Shelter was originally released in 2015 for mobile devices. The game was later ported to Nintendo Switch, PlayStation 4, Windows PC and Xbox One.

Bethesda said in its suit that Behaviour uses “the same copyrighted computer code created for Fallout Shelter in Westworld,” alleging that a bug evident in an early version of Fallout Shelter (which was later fixed) also appears in Westworld. Bethesda alleges the companies “copied Fallout Shelter’s features and then made cosmetic modifications for Westworld’s ‘western’ theme.”

The suit also alleges that “Behaviour breached its contract with Bethesda and utilized its restricted access to Bethesda’s intellectual property, including Bethesda’s copyrighted code, trade secrets, and other rights, to compress its development timeline, reduce costs, and quickly bring the Westworld mobile game to market, and offer players the widely popular gameplay experience found in Fallout Shelter.”

The suit points out similar gameplay features, including “cartoonish 2D characters in a 3D environment” and the underground multi-room facilities that players explore and build, in both Fallout Shelter and Westworld.

Bethesda is suing for copyright infringement, breach of contract and misappropriating trade secrets. The publisher is seeking a jury trial and damages.

Polygon has reached out to Warner Bros. Interactive Entertainment and Behaviour Interactive for comment on Bethesda Softworks’ lawsuit, which you can read in full below.

Update: Warner Bros. provided the following statement to Polygon: