If you just want to get to the point, skip this wall of text right here, because it's really just an introduction. But if intro's are your thing, or you just want to see where I'm coming from read it. I won't judge.
From what I've heard on this website, the general concensus is that people want their MMO sandbox flavoured. The people are saying that they're tired of linear, class based leveling. They're tired of restrictive, and funneled gameplay that promises stellar endgame content, and then builds an entire game to keep the players away from it. Instanced zones that are meant to cut the world into easy to swallow chunks, because who wants to explore a massive world if there's no carefully lined out content in it? I do. It seems to me that MMO developers have forgotten something important about MMOs. They've forgotten why we play them. We don't come to play them because they have carefully written story lines, carefully crafted worlds, or even just for the PvP, because frankly, MMOs don't have a great track record in any of those fields... If I wanted a story, I'd play a game like Mass Effect, or if I wanted PvP I'd play CoD4. We come here to interact with other players, and to build a world. An MMO's strongest point is that it's interactivity makes it unpredictable; You can be wandering around, killing monsters and run into an enemy player. Name one other kind of game that can happen in. Name one other kind of game where a guild can build a city, raise an army and wage war on another guild. Name one other kind of game with an economy that evolves in real time, or one other kind of game where a player can do anything he or she wants to do. A game should have less rules, and more decisions.
So let's get right down to it here. I'm planning an MMO, but I don't have the resources to make it. I'm just hoping that somewhere in the 7 or so readers I'll get for this someone will change the way they look at MMOs. And in this post, I want to get right down bones of my idea. I've never been great with following my own orders though, so wherever it ends up is up in the air right now.
Feel Free to skip passed this too, this is just the rationale.
Since in a sandbox a player should be able to define himself by his actions, and a guild should be able to shape the world, inherent factions have no place, and as such, races have no real importance at this point, we'll move right on to the class system. Afterall, the most important part of the game is the player, so we may as well start with them. Now, we want the player to be able to be whatever he wants to be, so classes are out. At the same time we still want him to develop his character, so the obvious alternative is a skill based system. Personally I'm not a huge fan of the standard skill based system, as they are rife with flaws. Every player turns out to be a Stealthy Battlemage, who also rocks at crafting. It's just that the logical path to go down is every single one at the same time. But I've found a way to keep variety in the game, and it also has the bonus, of allowing a player to respec his character into any class he wants. That system is a guild based progression.
Let's say that there are 100 possible levels to every skill. Naturally a player can bring them up to level 50 regardless of their guild, with the exception being magical skills, which can go up to 15, just because I think that magic should be more of a rarity. Now, a guild would get to chose what kind of Archetype they'd like to train their members in: Fighter, Rogue, Priest, Mage, Craftsman. From here they choose any 4 skills from their Archetype and 1 skill from any list they want. These skills can be maxed out. So if me and my friends start a guild, we might pick the skills Heavy Armor, One Handed Sword, Sheild, One Handed Axe, and Dark Magic. There you've essentially created the Dark Templar from AoC. That's the player essentially making the same content Funcom spent a month on in 30 seconds. And if the player wanted they could swap out Heavy Armor for Light Armor, and maybe instead of Dark Magic they pick Poisons, or maybe even Stealth. You can make whatever you want, and keep the variety in the gameplay. To respec, all you need to do is join a new guild. For all effects and purposes your skills would drop down to their new maximum. In case you regret your decision, your old skills would be remembered, but they would degrade over time. For example if you switch guilds and your new guild doesn't have the sheild skill selected, you would perform as if you were still at level 50 shield, but your skill would still be at 100, and tommorow it'd be 75, then the next day it'd be at 50. And that pretty much covers leveling.