In June 2018, Bethesda sued Canadian developer Behaviour Interactive as well as publisher Warner Bros. because of their Westworld mobile game, which they called a 'blatant rip-off' of Fallout Shelter. In fact, according to Bethesda, Westworld even contained copyright code created for Fallout Shelter by Behaviour Interactive.
Yesterday, with a very brief press release, Bethesda announced the 'amicable resolution' of the lawsuit. No further details were disclosed, but it sounds like Bethesda might have received compensation in order to drop the lawsuit, which is after all what likely happened with the lawsuit between ZeniMax (Bethesda's parent company) and Facebook, resolved in early December.