My Opinion
My View on Bethesda's Claim
In my opinion, Bethesda has a strong case based on the fact that the mobile game uses Bethesda's property. The layout, the premise, the code, the bugs, there's no denying the similarities.
My View on Behaviour's Defense
Behaviour Interactive's defense is less convincing. There are too many similarities between the Westworld game and Fallout Shelter. Seeing as Behaviour Interactive helped develop Fallout Shelter in 2014, then Westworld in 2019, it's hard to defend their case.
My View on Warner Bros. Involvement
Warner Bros.' involvement is a bit different. In my opinion, if Warner Bros. didnt know about Behaviour using assets from Fallout Shelter, then you cant blame them. Although someone from the Warner Bros. team should have done research to make sure no game was like theirs.
