Yesterday, we reported on the new Westworld mobile game. However, it looks like the app’s time may be shortlived as Bethesda is suing Warner Bros. and Canadian game developer Behaviour Interactive for allegedly using code from Bethesday’s Fallout Shelter mobile game. Here’s how Variety breaks down the case:

Bethesda hired Behaviour in 2014 to work on its “Fallout Shelter” app. “Fallout Shelter” is a free-to-play simulation game where the player builds and manages a post-apocalyptic bunker full of workers. The “Westworld” app similarly allows the player to build their own version of the eponymous theme park and interact with characters from the hit HBO TV show.

But it’s not just a similarity of gameplay. The games also share bugs in their code. Per Variety, “Bethesda points to specific bugs in the “Westworld” app as evidence of stolen code. Those very same bugs are in “Fallout Shelter’s” code, it said. For example, Bethesda claimed the demo version of the “Westworld” game includes a visible software bug that’s also present in an early version of “Fallout Shelter” code Behaviour delivered to Bethesda during its development.

That does not look great for Warner Bros., and the fact that they share a kind of gameplay, a developer, and similar code makes it appear, at least on the surface, that Behaviour lifted their Fallout game and just gave it a coat of Westworld paint.

For their part, Bethesda issued the following statement:

“Bethesda Softworks has today filed a complaint in U.S. District Court against Behaviour Interactive and Warner Bros. for copyright infringement, breach of contract, and misappropriation of its intellectual property. The case arises from Behaviour’s development of a ‘Westworld’ mobile game for Warner Bros. Behaviour had previously worked with Bethesda to develop Bethesda’s hit game, ‘Fallout Shelter,’ and under that contract, Bethesda alone owned all resulting intellectual property, including the game’s copyrighted code. “Behaviour illegally used the same copyrighted source code from ‘Fallout Shelter’ to develop ‘Westworld,’ and copied Fallout Shelter’s game design, art, animations, gameplay features, and other elements. As a result of Behaviour and Warner Bros’ unlawful conduct, ‘Westworld’ is a blatant ripoff of ‘Fallout Shelter’ with largely superficial, cosmetic changes.

Warner Bros. and Behaviour have yet to respond.