The lawsuit pertains to the similarities between Fallout Shelter and Westworld.
Now unlike PUBG suing Fortnite in Korea, this one actually has some merits to it, at least at first glance. The summary of it is that Warner Bros. employed the same company previously working on Fallout Shelter, who used the code and assets that are legally the property of Bethesda.
Taken from the text of the suit, it states: Warner Bros. expected and relied on Behaviour’s ability to reuse and/or leverage Bethesda’s computer code, game designs, and other intellectual property as the foundation for the Westworld game. This unauthorized copying and sharing enabled Behaviour to shorten its development cycle, reduce costs, and decrease the game’s time to market and to command a built-in consumer base by making the Westworld mobile game’s gameplay experience and look-and-feel the same as or substantially similar to Fallout Shelter.”
Forgetting for a moment the fact that you can’t (or at least shouldn’t be able to) sue over gameplay elements, the source code is definitely something Bethesda owns the rights to, so if they can prove Westworld was developed using it, it is indeed a clear cut case of copyright theft.
Humorously though, the lawsuit also claims the bugs frequenting Westworld as constituting a proof, their logic being that these are the same bugs they experienced when developing the game. Which kind of means they’re trying to establish a trademark on their bugs, which ironically makes sense, the gamer perception of Bethesda games as bug-riddled has persisted for years.
Perhaps less outrageous and more nuanced than the PUBG lawsuit but still pretty funny.