Gonzalez said it's best not to settle on themes too early. While some are obvious (New Vegas would doubtlessly deal with greed), others may seem right but wind up not fitting on further reflection. For example, Gonzalez said he stayed away from the theme of luck.
"New Vegas isn't about luck," Gonzalez said. "It's about having a rigged game."”
At Obsidian, the first step was extensive research. Gonzalez played through the first two Fallout games, originally released on PC in the 1990s (he said the games still held up), and revisited Bethesda's 2008 game Fallout 3. The Obsidian team watched movies that captured the Fallout tone, like Dr. Stranglove, and also Vegas-themed films like Casino and 1960's original Ocean's 11.
Books like The Last Honest Place In America by Marc Cooper and The Green Felt Jungle by Ed Reid and Ovid Demaris also gave the team inspiration during the research process.
And even though Fallout: New Vegas is a fictional game, Gonzalez said that non-fiction books are particularly helpful when creating a new world. "You'll just uncover an incredible wealth of stories that will inspire content for the game," he said.”
There are issues with domesticating tribals and forcing them into one view of the world, there are issues with treating a wonder of the old world as nothing more than a bloody battleground, there are issues with propping old flags from Rome and California without a clear understanding of what those flags represent, and the long-range perspectives of many characters you'll encounter in the world have strong opinions about what's going on in the present, all born from the elements above. The question of the Old World making itself heard in the present - in the Mojave - is a core theme in Fallout: New Vegas, and whether overt or not, we hope it sinks in with the player as well.”