Depends how you look at it. Obsidian was more like a modding team than a game development team for New Vegas. They had the engine and all mechanics ready to use. All they had to do was minor tweaks and new content. So essentially modding, not developing a game.

Arguably, most of ‘game development’ these days is more akin to ‘modding’ from 10+ years ago, so the terms kind of lose their meaning. But New Vegas was made in 2008-2010, so I think it fits.

As we can see years later, games made by Obsidian from scratch aren’t nearly as good. Perhaps what made New Vegas great was the mix of Bethesda and Obsidian. Or maybe Obsidian just lost their edge, like most studios, sadly.