It's based on fallout as a whole, not just NV.

It's like it's own addition to the series. It's quality is so good it feels like a new game released kinda. The show even has that re-watchable trait just as the games have a great re-playable trait.

Think of it as Fallout 5.

Pretty much every entry in the series tells a standalone story but pulls on the threads laid down in others. And the show is no different. It pulls most heavily on the West Coast narrative since it's set mostly around L.A.

In that way they're all "based" on each other while being their own thing. It's part of what makes Fallout so accessible.

It's not based on any specific game, it's its own story. But it uses the worldbuilding and lore from different games to create a recognizable Fallout setting.

I like to think about it like this:

Lucy: fallout 3: grows up in the vault, walks out cause her dad is gone, finds a the town. Just like in fallout 3, we walk out and find megaton.

Max: fallout 3 and fallout 4: centralized around a the BOS, sees the pros and cons. In fallout 3/4 we are forced to make decisions that could change the wasteland. Clean water for the brother hood? Eradication of all things not human, confiscate pre war tech, or share it with gen pop so they can thrive? I think his story will enter twine with the BOS outcasts at some point seeing as there’s SO Much story behind the chapters of BOS and the zealot outcasts. ( Edit) also based on the elders comments, sounds a lot like what a put cast would say, “ BOS isn’t what it once was”

Coop/ Ghoul: New Vegas: there’s a lot to touch here, big piece here is his direct ties to vault tech through his wife. We’ve seen a glimpse of Mr. House, and the Strip. We’ve seen his run in with the NCR and BOS. He seems to lean a lot more towards the NCR obviously but still has opinions about the other factions as well. Which in New Vegas, we are also faced with lots of factions all fighting for similar reasons, which non are clean. So pick your evil or stay alone. Which (in my opinion) is 50 precent of the plot in NV

Just my opinion based on the games and series. All in all, I need more.

The Fallout series is based on…Fallout.