About Age of Decadence: it's a good game that experimented into a certain direction and succeeded at doing what it wanted to do. But is this the direction RPGs should involve into? Or, on a more subjective level, is it the direction I would like RPGs to develop into, or the direction I would have developed the Fallout/Arcanum style of RPG into if I had been in VD's place? No, it's not. Which just goes to show that there are so many different potential avenues for the classic RPG to develop into, and AoD is just one of those avenues.
While AoD serves up a massive amount of choice and consequence for the player, it also feels like it's railroading the player to a certain extent, and focuses more on providing the player with a couple of distinct paths than it focuses on providing the player with an open playing field filled with role playing opportunities. In this way, as inspired as it may be by Fallout and Arcanum, it deviates rather significantly from those two games. In Fallout, you're released upon the world and can go anywhere and do anything right from the start. Go to Junktown, help either Gizmo or Kilian, or neither of them, just ignore it, don't even have to visit the place. Same with every other place. The game presents you with locations and quest opportunities, and some quests are mutually exclusive, and some offer choices that affiliate you with a certain faction, but you can also just ignore everything and head straight for the water chip and then the Master if you have previous game-knowledge and know where to find them. Similar with Arcanum: while this one has a more linear main quest with more steps in-betweeen (go to BMC, go to Wheel Clan, go to Qintarra, find Min Gorad etc etc), every location in the game offers you several quests, sometimes with conflicting sides to choose, and you can do whatever you want. You're never railroaded into anything and often get the opportunity to double-cross your employers, too.
Let's take the first town of Arcanum, Shrouded Hills, as an example. The gnomish wizard Jongle Dunne offers you the quest to destroy the town's steam engine cause he hates technology. The steam engine is guarded by a simple-minded dwarf who loves steam engines and is a rather loveable little dude. He attacks you when you attempt to wreck the steam engine, and usually this will end in his death, but if you dump Virgil outside and just get the dwarf to low HP so he panics and runs away, you can destroy the steam engine without killing the poor guy. Quest solved, you can collect your reward. BUT WAIT! If the dwarf survived, unlikely as it is (because most players will have Virgil with them who'll chase the dwarf down even if he flees), the town's constable will be pissed at you a few days later because the dwarf told him that it was you who destroyed the steam engine! Oh snap! This makes him refuse to talk to you about anything else, so you can forget about all the quests you can do for him. Now, if the dwarf is dead and the Constable doesn't know it was you who wrecked the engine, he'll ask you to fix the engine, which you can do by bringing him a large gear found in the nearby mine. BUT if you fix the engine for him, Jongle Dunne will feel betrayed by you, and he won't talk to you anymore. He has a second quest for you and is a trader, so both of this will be closed for you. Of course, if you know how to game the situation, you will solve Jongle Dunne's second quest for him first, and only THEN fix the steam engine. But to game the system this way, you need to know all the different factors involved in this questline, and it's really easy to accidentally piss off someone, but it's always clear and reasonable why they're pissed at you.
This is great quest design with choice and consequence that doesn't force the player into a railroad. You could describe Arcanum's quest structure as having several quest hubs the player can enter, and within those hubs he has a lot of quests available, some of which are mutually exclusive, some of which can block other quests or can piss off an NPC, etc.
AoD's structure is more of a tree-like structure with several branches, which all have branches of their own. So you have the legion branch, the assassins branch, the merchants branch, the thieves branch. Within each of these you have at least two branches, too. But once you're within a branch, you can't hop over to another. Like, if you joined the assassins you can't betray them for the thieves and join them instead later on. You can only make choices that are applicaple within the assassin branch: there's no "I'll betray my faction to the leader of another faction" kind of thing. If we were to apply that Shrouded Hills steam engine quest to AoD's structure, it would look like this: you can either choose to work with Jongle Dunne who hates tech and wants the steam engine destroyed, or team up with the constable who supports the town's industrialization. Within each NPC's quest path there are choices to make, including betrayal of your original employer, but you can't switch over to the other side at any point. Once you made the choice to either go with Dunne or the constable, you're in either the "Dunne path" or the "constable path".
That's how most of AoD works. There are many choices of paths, but once you've locked yourself into a path, you're in it, and the different paths don't overlap. While there are interactions with other factions, it never goes to the point where you can just switch sides, leave your current faction and join another. The game does what it does really well, but this structure is why many people call it a "glorified CYOA book".
Furthermore, AoD's path-railroading becomes all the more apparent when you give yourself additional stat and skill points with Cheat Engine (yeah decline blah blah casual blah, fuck off I like exploring options on my second playthrough by giving me high stats in everything and seeing where that can get me), because you'll realize that most of the skills you raised are completely useless unless you're following the path associated with them. Lockpicking, for example, is only used in the thieves questline. When I played an assassin, I was surprised how the thieving skills were essentially useless and the only real viable character builds were critical strike guy and combat guy. Same with the merchant, you essentially have to play a talky guy and stealth skills, for example, are useless. Even though it would have been cool to approach a merchant's guild quest with stealth by breaking into the mansion of a guild rival, stealing some blackmail material, then using that against him instead of your speech skills.
But this isn't how AoD's quests work: the quests are essentially CYOA style affairs with different choices and skillchecks, and consequences based on your choices and whether you manage to pass the checks or not.
This is quite different to a more goal-oriented and open quest design as we can see it in, for example, the first quest in Gothic 2: get into the city. There are multiple ways to get into the city, but the game never puts the choice before you and says: "Now you have these three methods to choose from: become a farmer so they let you in as a citizen, pay them a bribe so they let you in, or sneak around the wall and find a back entrance." Instead, you have to figure out these options by yourself and then choose the one that seems best to you. This is the kind of quest design that just puts a goal in front of you, then lets you tackle that goal with all the tools the game provides you.
And that's the direction I would take the classic RPG into: an open quest design where you're confronted with goal-oriented quests (get X, find out X, kill X etc) and then you can tackle these quests in any way you want, depending on the skillset of your character. Stealth, combat, diplomacy, all are valid approaches. In AoD, there is often only one approach that is truly valid, and that approach depends on which faction questline you are in. Going through the merchant questline as a pure fighter or pure stealth guy is impossible, or at least will end up giving you terrible results because you suck at all the options the quest presents to you, while the quests never allow you to make use of those skills you actually possess.
Now, AoD is a good game, and certainly a game designers can learn from - both as a positive and a negative example - and I wouldn't mind receiving more games of its kind. I'd certainly play an AoD2, and will play The New World when it's out. But it's not the direction I would have turned the genre into, and I doubt it's a direction anyone else but Vince would have chosen to go into, to be honest.
Which is why creative new designers who have a certain vision and know where they want to go are so important. AoD is a game of that kind. It doesn't fucking matter how influential it is on other developers or how well-known it is, what matters is that AoD itself is a game that took RPGs into a new direction because its lead designer was a guy with a vision who knew what he wanted to do, and he went into a new direction nobody had gone into before. If that isn't what evolving the genre is, then I don't know what is.
Thing is, the game is out there and can be played by anyone. Maybe a 12 year old kid just received a cracked copy of AoD on a DVD from a friend who said "check this out, the cracker who sold it to me told me it's awesome" and then he plays it and is amazed by the amount of choices the game throws at you, and 20 years later that kid works as a quest designer and takes inspiration from AoD. That scenario is entirely possible. Because that's exactly what happened with me and Arcanum - pal had a cracked CD with a new game, we installed it, played it, and the game blew us away, and that game was Arcanum and now I somehow managed to get into game design myself and write quests for an RPG and my idea of RPG quest design is heavily informed by Arcanum. But when you look at the industry as a whole, Arcanum can hardly be called influential.
A game is influential when someone, somewhere, somewhen is inspired by the experience of that game and makes his own game which is partially informed by that experience. AoD may very well give some people who played it new ideas on what to do or not to do with an RPG. Maybe in 10 years we'll receive a really good new indie RPG and in an interview the lead designer will mention how AoD was his main influence. Who knows?
But what you can't deny is that it evolved the genre by embarking into a new direction. That's a fact. Doesn't matter how influential or well known it is.