The case has now been settled, however: Bethesda and Behaviour released a joint statement yesterday saying that the "have amicably resolved the lawsuit Bethesda brought against Behaviour and others related to the Fallout Shelter and Westworld mobile games". Fallout Shelter had originally been created under contract with the stipulation that none of the assets or code would be reused in other projects.
Filings with the United States District Court in Maryland, where Bethesda is located, show that Bethesda and Behaviour came to terms on a settlement in principle back in November 2018.
According to the Fallout developer, the lawsuit was resolved "amicably".
Past year we reported that Bethesda had launched a lawsuit against Warner Bros. While Warner Bros. Entertainment goes unmentioned in the update, the conclusive tone seems to indicate that the publisher was indeed included in the resolution. Turns out, it might have a bit too much in common with that game, as Bethesda is suing Warner Bros. and Behavior Interactive, the developers contracted to make Fallout Shelter for Bethesda. Bethesda claimed that the Westworld game was a little too similar to their vault-building title Fallout Shelter.
On top of that, there were some bugs in Westworld that were in an earlier version of Fallout Shelter, making a strong case for Bethesda's claim. It even called Bethesda's allegations "untrue" and "baseless" at the time. Westworld remains available as a free-to-play game on iOS's App Store and Android's Google Play store.