Not only does Fallout 3 have a better map design than any other Fallout game, but it also has the most free map design out of any Fallout game. Take for instance where the player starts the game on the map. It is pinpoint in the middle, not to North or the West and close to an invisible wall, deathclaw sanctuary or anything restricting. This effectively encourages exploration of it's already well-designed map.
Exploration doesn't mean "Go wherever you want without consequences"
It means you can go wherever you want but the game reacts realistically to your decisions on where to go. If you go down the road that everyone says is dangerous and will kill you, the game shouldn't hold your hand and say "It's fine, don't worry about it".
In Fallout 1, the final location in the game was right next to the beggining area, but it didn't matter because it was guarded by Supermutants which you wouldn't be able to take on immediately.
This is the point of a Fallout Game: having a world where you can take it at your own pace without being railroaded, however the game doesn't hold your hand and make it easier if you're going somewhere unprepared. Fallout 3 fails astronomically at this.
Fallout 3 follows a philosophy of quality > quantity. While some have criticized it for having less side quests than several other Fallout games, Fallout 3's side quest are arguably the best designed quests in the franchise. Take for instance the Superhuman Gambit, an excellent showcase of how campy yet grounded Fallout can be, without straying into Wild Wasteland or Fallout 2 territories. The Power of The Atom showcases just how scenic and fun a side quest can be, as well as how impactful it can be on the environment. Never before or after Fallout 3 has a side quest ever managed to pull this off.
Fallout 2 fanboyism kicking in: I'm going to say this is bullshit for a variety of reasons:
1. Dismissing Fallout 2's content as Silly and Over the top, while defending Superhuman Gambit is ridiculous. Most of Fallout 2's side quests deal with economic inter-relations between towns, and coming to consensuses between communities that are at odds with each other. Most of Fallout 3's side content
You could say overall that Fallout 2 is more ridiculous, and I'd agree, but in terms of Side Quests, Fallout 2 offers consistently serious and interesting choices, pretty much all of Fallout 3's content is "Haha wouldn't it be funny if we had Superheroes, hahaha", or "Hahaha, do this quest for a town full of children for no reason other than it being mandatory to complete the game"
The problem with Superhuman Gambit, is that it has no serious stakes, and is basically just a dumb distraction, akin to anything on the level of Fallout 2. You can say it's grounded because "They're not actually superheroes, just people with issues" or whatever, but it's still solely written for the rule of cool and to be like "Haha superhero fight".
It also adds basically nothing of value to the Fallout Universe. In Fallout 2 you have quests about sorting out a conflict between a farming town that's dying from lack of clean drinking water, and a colony of underground mutants who have been isolationist their entire history, and used local mythologies about farms filled with ghosts to scare people away from their farm to keep themselves safe, and if an agreement isn't reached, the farming town will die.
The whole premise of Ghost Farm is silly, but it actually creates an interesting interconnected world. Superhuman Gambit is probably one of the quests with the most actual stakes in the world, and nonetheless there's very little actual meaningful impact anything you do has. It's nothing like the equivalent quests of Fallout 2 where you're deciding the fates of entire towns access to vital resources based on how you deal with what seemingly at first is a silly faction.
2. Fallout 2 has way more fleshed out and high quality side quests than anything Fallout 3 offers. Let's do a basic point of comparison between interactions you can have with Gecko and interactions you can have in Power of the Atom
In Power of the Atom you're basic choices are Nuke a town for vague reasons that are never really justified to be BWAHAHA I'M EVIL. Like literally, commit genocide for shits and giggles, or repair the bomb and have everything be fine. That's it, that's the scope of your interaction.
In Gecko, you can start the quest in one of two ways: Either from the First Citizen of Vault City telling you that there's an issue with polluted groundwater from Gecko's broken reactor, or from Harold mentioning the polluted groundwater, and needing a part from Vault City to fix it. This immediately sets up the stakes between Gecko and Vault City: The towns are at odds with each other, one being a violently xenophobic anti-mutant state, the othr being a mutant community, however nonetheless their needs overlap. The repairing of Gecko's reactor isn't just for Gecko, it's literally vital for the survival of neighbouring communities because Gecko isn't an island, it's interconnected with nearby towns.
Now at first glance you have the same choices: comically evil blow up the entire town because BWAHAHA I'M EVIL, or fix the reactor. However, Fallout 2 being Fallout 2 isn't content to just stop there, and actually fleshes it out a lot more: See, beyond just being able to fix the powerplant, you can also OPTIMISE it. Gecko can produce excess electricity if it wants.
If you've been paying attention up to this point, you'll probably also realise that Vault City's generator isn't enough to keep up it's expansion, so they're having to institute major policies to reduce population in order to not overuse resources. And Vault City is hostile to Gecko, so Optimising their powerplant isn't enough on it's own: rather doing so will cause Vault City to forcibly annex Gecko and take it over by force.
Rather, what you need to do is follow Gordon's advice and create a trade deal between Vault City and Gecko, so Vault City relies on Gecko's powergrid to keep it's city up and running. This is one of the steps you need to take to stop NCR Expansionism up north.
This is the core difference between the original Fallouts and Fallout 3.
In terms of quest design, the original Fallouts add complexity, and then keep piling it on. Some of the quests from the Originals are masterfully designed: Gecko and the sheer variety of outcomes is actually a minor point: Fallout 1 has genius quest design when it introduces you to the conflict between Gizmo and Killian entirely organically by having a guy show up with a shotgun to kill Killian. You don't need the "Please give me a quest" button.
Even in Fallout 2, pretty much every major town quest is started by inquring about the G.EC.K, seamlessly blending the side content with the main content. To even find the majority of the content in Fallout 3 you literally have to go off the beaten path and find a town in the middle of nowhere. The game is literally designed in such a way that the content is not only disconnected from the rest of the world in terms of the world not being a coherent world where towns have consequences on one another's existence but rather a series of islands that seemingly exist disconnected from the rest of the world, but also disconnected in that the game gives you no plotwise reason to visit anywhere, whereas Fallout 2 gets you invested in towns by putting them in your direct path to solving the mystery of the G.E.C.K
Fallout 3 certainly has better quest design than Fallout 4, but it's by no means anywhere near as organic or complex or well-designed as the originals, and every single area feels like an island of silliness that solely exists for the player to do one or two quests in, rather than part of an interconnected world.
Fallout 1 and 2 create vast interconnected worlds where the fates of towns are often connected directly to one another, the major power players have impacts on the entire world at large. Nothing is an island in these games, everything is inherently related to everything else, and often the quests are designed in such masterful ways that it puts Fallout 3 to shame.
Fallout 3 possesses the most beloved and iconic factions in the franchise, the Enclave and the Brotherhood of Steel. Some have criticized Fallout 3 for having an angelic BoS too uncharacteristic of Fallout 1's Brotherhood. This is addressed in lore in how the Brotherhood Outcasts came to exist. The BoS in Fallout 3 is Lyons' chapter of the BoS, who set aside their main goal of capturing technology to use it to help the Wasteland prosper. When combined with James's goal to purify the Potomac river, one can see why the BoS in Fallout 3 is so much more understandable and human than any other iteration of itself in the series.
"Posseses the most beloved and iconic factions of the series" Wow so it has the Master's Army in it?
Jokes aside, this is literally a ridiculous point: "Fallout 3 is good because it has these groups that the other games in the series has" is kinda a dumb point. Like yeah, it has the Enclave and the Brotherhood, because it ripped them out of other games, and placed them on the other side of the continent for no good reason other than to slap a Fallout label on them.
"This is addressed in the lore" is also a Bethesda fan's favourite arguement to try and refute genuine criticism of the games. It also doesn't work as an arguement. See, if you have any sense of nuance, you'll realise that criticism of the way Supermutants and the Brotherhood are handled in Fallout 3 don't amount to "Their done differently" but rather "They're done wrongly."
People dislike the Brotherhood because they're main goals amount to being the good guys and helping people, and shooting up Supermutants to help clear them out. They don't really have discernible goals beyond being generic good guys who do good things to help people. Yes it's handled in lore why they turned out this way, but this doesn't make them portrayed in an interesting way.
In the same way that there's technically lore-reasons why Supermutants are the way they are in game, but that doesn't change the fact that Supermutants in Fallout 3 are generic Orcs which solely exist to be meat targets to shoot at and enemies, and don't have anywhere near as much complexity as players expected from Supermutants.
Writing a lorewise explanation for why a group exists in a certain way doesn't absolve you of responsibility for writing them in a way that captures what made them interesting and good in the originals.
Also you argue the BOS are more "Understandable and Human". Yeah, when I think of an Understandable and Human character I think of Superman. His desire to help people and be perfect in every single way is so relatable.
No, when I think of being Understandable and Human, Fallout 1 and New Vegas are clearly the victors here, in that they may ultimately desire to do the right thing, but they're still at the mercy of internal power struggles and material needs.
In Fallout 1, the Brotherhood are just a society, one that's militaristic and has a strict heirarchial structure, as well as a veneration for their founder, but still just an ordinary society. They have a vague ideology about preserving technology to help future generations, but that ideology is always secondary to their main needs: They're far more interested in trading for their own survival and looking after lost paladins than they are being ideological purists.
The Brotherhood will eventually help reintergrate the technology they've preserved in to society if Rhombus takes control, but there are also other hardliner factions who could instead opt for war with the outside world. In other words, as per their presentation in Fallout 1: They're mostly interested in helping rebuild the outside world, but they're far more interested in being a close-knit society dedicated to their own survival, as humans would be, and the internal politics of the Brotherhood can hinder their goals sometimes.
Fallout New Vegas shows the Brotherhood battered and defeated at the end of the war, having to survive on subsistence rations because the current High Elder has decided for their long term survival it'd be better to stay underground and hidden from the outside world. Because of this, the Hardliner factions within the Brotherhood are getting antsy, instead suggesting that they should simply reassert themselves and try and gain some level of control over the Mojave, and with much of the population disliking their hiding underground, they are gaining so much popularity that most of the Brotherhood are willing to basically replace the High Elder over a legal technicality.
The problem is however, if the Hardliners took control, they'd be way less willing to negotiate with the NCR, since they came to power promising to assert force in their own defence, whereas MacNamara, since his entire point is that the Brotherhood should survive even if it means surrender, is far more willing to negotiate.
Basically, New Vegas shows the political struggles of a Brotherhood trying to survive at all costs after a destructive and costly war, and the various factions that emerge from that. That is far more human than anything Fallout 3 does.
Being Generic Good Guys is neither understandable nor human. Wanting to help people for the sake of helping people, and facing no adversity for it is neither understandable nor human.
What makes the Brotherhood understandable and human, is ultimately having good intentions, but being more interested in preserving their own society, to the extent that often the internal needs and politics of the Brotherhood directly interfere with their goals.
I mean if we don't count Childkiller bounty hunters in FO1/FO2 and bounty hunters in Fallout 2 that attack you for having more than 501 negative Karma, absolutely yes.
Fallout 2 literally has Wanted Posters start showing up everywhere if you have negative karma, or evil related reputation perks.
Multiple stores close down if you kill their owners, with "Closed for business" signs appearing.
Fallout 1 has Necropolis razed to the ground if you leave it long enough.
This guys arguement of "Fallout 3 lets you have a major impact on the environment" doesn't really add up since
A. They did that to do what's called "Frontloading". Having a nukeable town in the first part of the game is designed to give an impression that this is what the entire world is like (and clearly it's worked), nothing of the sort exists anywhere else.
and
B. Fallout 1 and 2 have a WAY more interactive and changing world, consistently throughout the game. They don't need a flashy "Nuke a town" for it to be the case.