While it's a ton of fun, it's still a fundamentally linear game at its heart.
You might want to change that sentence. One of the very reason Fo1-Fo2 are still highly regarded today is that they amongs the most non-linear games released to this day.
On the other hand, amongs the many things that crippled Fo3 is that total forced linearity that is totally contradicting the very soul of the series.
Fallout 2 is very much non linear, which is why I didn't mention it. Functionally speaking, the main "story" of Fallout 2 and 3 is the wanderings of the Chosen One and Lone Wanderer. For example, New Reno was practically a game in and of itself. The best way to explain this is to look at Fallout 2's ending slides. Very few of them have to do with Arroyo or the Enclave. Rather, they're all about what you got up to on your way to the G.E.C.K. Just look at all the sub plots in the game. The war against Jet and Slavery (Crime and Anarchy vs Order) which is the core of the Den, Redding and New Reno's storylines. This is then tied into the NCR, when you can join the Rangers. Or, the issue of uniting populations in forging a new order (Modoc, NCR and Vault 15, Gecko and Vault City). Ect. Relatively little of the content is solely linked up to the Arroyo and Enclave plotlines, though the Enclave's presence in the wastes is cleverly tied into the storylines in many points.
The same goes for Fallout 3 in a way. There is a reason the PC is called the Lone Wanderer. The story there is of a scared kid who leaves the vault and wanders about the wastes. Though there is a main plot, in terms of the content dedicated to it its relatively minor in scope, reflecting the fact that this isn't a huge region we're playing in, its a city and the surrounding areas. Whereas Fallout 2 and New Vegas basically have you resolve everyone's problems, Fallout 3's PC is a much more mundane character. You help bring water to the wasteland and are one of the key soldiers in the war against the Enclave, but the world's fate doesn't revolve around you. The capital wastes was surviving before the fresh water, it can survive without it. While this makes for a blander story, it also can be kind of refreshing at times. When I play Fallout 2 I know that the fate of each city revolves around my choices. While impactful and fun, it's also very cliche in a way. You're the all powerful agent without whom each town would suffer. Meanwhile, part of Fallout 3's appeal to me at times is that in the end I'm just some guy wandering about, scavenging for good shit to make some caps off of. If I become a slaver the whole capital wasteland doesn't become a slave state dun dun duuuuuun. I'm just a bloke enslaving for caps and giggles. It's also why I love the capital mall as a general region. More than any other place in the game, this is where you get to feel
powerful. In Fallout 2 I expect to be the all conquering hero. In Fallout 3, I'm just some wanderer, so cleverly fighting my way through trenchworks and taking out both an army of Talon Company mercs and super mutants feels damn exciting. Once again, I have a ton of frustrations with the game, but no other game in the series just lets you drop in for an hour or two when you get bored to do some random shit.
Now, let's fully address why I called Fallout 1 linear. Much like Fallout New Vegas, the main story of 1 and NV is the main story, if you get my drift. Many of the major sideplots of the game are tied into the upcoming battle for the dam, or the struggle against the super mutants. In fact, contrary to 2, most of the ending slides are based upon your decisions in the lead up to the dam. While on the one hand this does place you more firmly in the story of the game, on the other it does make you feel like you are under pressure to follow the story. It's not really a place where you can feel like dropping in for an hour or two to raid a place and then leave. Each action you take you do under the knowledge that the Mojave's fate rests on you. This is great for RPG play, but it also strips some of the freedom you feel in 3.
1 is even more blatant in this. While there are other paths to do the main quest in 1, most of these really only happen when you are replaying the game, often with the benefit of the wiki. For most people who played Fallout 1 without preknowledge, the game set them down a fairly set path. There were different ways to overcome the obstacles on the path, but it was still a clear line to follow. For example, few quests tie into other towns in a way that give a sense of life to the place. You need to join the Brotherhood to help you fight the mutants. They send you to the glow, you come back and are allowed in, unlocking the tools you needed to finish the game. Most of the sidequests, barring the "take down Decker and Gizmo" storylines, are really about unlocking tools and knowledge on your way to accomplishing the main task. The time pressure placed upon you by first the water and secondly the rise of the mutants emphasizes this. Whereas in 2 you have places like Modoc that have nothing to do with the main storyline, Fallout 1 is a much tighter experience. Adytum is the only region which feels a bit freer and that's because the Follower's of the Apocalypse were stripped of a lot of their content involving their conflict with the children of the cathedral. Not to mention the fact that the main use of the gun runners and adytum is to get you the upgraded endgame gear you'll need to fight the master and mutants. s why 1's atmosphere and story feel so much tighter than 2, for good or for ill. From the time you hit Shady Sands, you are being built up to encounter the deathclaw and find the water chip, this reaches its apex once you reach the hub and the deathclaw is used to transition you to the super mutants. Its a wonderfully executed story, but it's still fairly linear in design.
To reply to Torrent, glad you were able to get someone else into Fallout! RPG's with a focus on pre game character creation are a bitch to get into without a wiki guide and personally I tend to prefer that Fallout NV style leveling where stat choices are less important than skills is really nice. It avoids the "fuck you you played the game wrong" tendency of early rpg's where poor choices make the game impossible to get out of the gates on. Instead you improve the areas that you like using and the game then rewards you for certain choices in quests.