From ew.com:

The long-awaited series, based on the 1973 film by Michael Crichton, is set to debut on HBO this fall. Our show is about the robots who dont realize theyre in a fake Western, showrunner Jonathan Nolan said during a panel at the ATX Festival in Austin, Texas earlier this month. Nolan added, It was actually Game of Thrones that made us feel like we could pull this off. We actually pitched this as makingDays of Heaven and Alien simultaneously and then cutting them together. Game of Thrones was the inspiration for this. Thrones had this commitment to practical production value, which is not necessarily whats in vogue these days [Westworld] had to have this big scope.