I'm not even sure where to begin given the nature of this style of game. I think I just typed my post around 4 or 5 times and had to begin again. Let's start simple and then if we get rolling we can talk in more detail.

First off how many of you are even familiar with sandbox style mmo/rpgs?

If you are familiar with them what would you say the demand is for that style of game today?

And the last question is what was the last game in this style you remember and what were your thoughts on it?

At the moment I am trying to get some general feedback on this particular style of game. I have ideas sure but for now I need to find out what people think of the style in general and how well it could even do in today's age. Depending on what kind of feedback I can get I will move forward with my concept a bit or maybe change how I decide to progress here.

Your asking us details on a concept so generalized, its impossible to do so.
Sandbox is literally "free roam". A concept that the player is given a world, and the choice of what to do with said world. Therefore the only way to make your game successful is by creating "prolonged gameplay + replayability".
This means that the gameplay must be enjoyable over a long period of time, and not lose its fun factor after one playthrough. This is the basis of Sandbox creations, and its the only way to make them successful.

If you wish for a good reference on these sort of games to start you off, either visit Don't Starve or Minecraft. Both are true sandbox games, and will give you an idea of what you can accomplish with them.
And yes, Sandbox games can have an ending to them. But they always give it as a choice, otherwise it would just be a story game. Minecraft does this, with The End, but allows you to play after.
If you want to see more of a strategy-based Sandbox game then a survival-based one, look up Triple Town. It's a simple game, yet elegent, and its concept is as original as it gets. Another one is Age Of Empires. Yes, it is a sandbox game.

Your asking us details on a concept so generalized, its impossible to do so.
Sandbox is literally "free roam". A concept that the player is given a world, and the choice of what to do with said world. Therefore the only way to make your game successful is by creating "prolonged gameplay + replayability".
This means that the gameplay must be enjoyable over a long period of time, and not lose its fun factor after one playthrough. This is the basis of Sandbox creations, and its the only way to make them successful.

If you wish for a good reference on these sort of games to start you off, either visit Don't Starve or Minecraft. Both are true sandbox games, and will give you an idea of what you can accomplish with them.
And yes, Sandbox games can have an ending to them. But they always give it as a choice, otherwise it would just be a story game. Minecraft does this, with The End, but allows you to play after.
If you want to see more of a strategy-based Sandbox game then a survival-based one, look up Triple Town. It's a simple game, yet elegent, and its concept is as original as it gets. Another one is Age Of Empires. Yes, it is a sandbox game.

He did specify MMO, however, so that changes things up a bit.

A recent one coming out is Darkfall, but that is developed by a lackluster group of individuals. I don't consider it as a serious entry into the market.

The last sandbox MMO I played.. was Eve, I enjoyed it, but it didn't captivate me very long.

I think sandbox MMOs can be great, but honestly OP, I don't see the point in gauging markability/player enjoyment from a section that averages maybe 10 posts per thread. Feedback is FOR the concept, not a precursor TO the concept. Approach this more statistically - look up games that are sandbox MMOs, look at their forums, look at other MMO forums, maybe create a poll on each one?

If that's what you want to make, then make it. Unfortunately, the chance of more than a few people ever playing your game is slim so it gives you a great excuse to ditch popularity and pursue YOUR game. I call it "positive negatives" - be realistic, but still keep things optimistic.

///First off how many of you are even familiar with sandbox style mmo/rpgs?
*Minecraft, roblox, dwarf fortress (is planetside 2 a sandbox? it is a big world...), king arthurs gold... I think i only like games with sandbox elements (kerbal space program?)

///If you are familiar with them what would you say the demand is for that style of game today?
*I love sandbox games where you need to use the game mechanics and their restraints to do something cool while also overcoming any environmental obstacles. The games i like the most have let me build things, and by building i dont mean building something physical like a building (a very boring object...) but building a complex system, for example a minecart track, a game, a castle with traps and good flow of friendlies etc. Would love a spaceship building game with flow of electricity and oxygen and fuel etc.

If everyone was/is like me there would be a great demand. But i dont see many such games. Perhaps because such games are complicated and require good tech (processing power, internet speed if multiplayer...) and dynamic (hard to control). An FPS where all you need to do is shoot people to be an average player is easier for both the developers and the players. (for players the best would be a combination but thats even harder to develop)

///And the last question is what was the last game in this style you remember and what were your thoughts on it?
*I guess you want it to be multiplayer sandbox (rpg?) so ill talk about King Arthur's Gold. Not really RPG in that you dont have a permanent character and its defined by its changeable class and amount of resources you carry currently, but anyways.
I liked it because the terrain is dynamic. The castles can be built anywhere, there may be any types of traps in any configuration, and your team might be pushing through from any point. As such the gameplay is always different, there is a lot of action and teamwork, and your actions are important. So the features that were good are probably:
-The action is always of a different type at a different location and as such there are different problems for you to solve to help your team
*If you are defending, your team needs to build good arching spots and fix stuff (what if they are coming from underground?)
*If you are attacking you need to get your team over their defenses and kill their archers and prevent them from fixing. You might get on a catapult and be launched to their side to cut a tower down or block a vital passage, or you might tunnel to get their flag while they are focused on defense

-There are many different roles. Not all players like building. Not all like sitting in a tree blindly shooting arrows towards the enemy and being happy about the gold that you suddendly receive once in a while.
*Some players want more action and less creativity. Let those people do tasks like defend or kill enemies, being creative in smaller things like character customization or decorating their home
*Some people want to strictly build and create things and rage when the tank they carefully crafted gets damaged. Let them do the things that you cant have everyone doing. Building buildings, playing around building 8 bit computers with cool new game mechanics while others are dying for their team.
*Some people dont want much action but dont really want to create anything either. Let them just support others or do some non vital tasks like mining some resources or carrying some ammo to the battlefield.
*People of course want to do different things at different times so the roles shouldnt be strict. But you shouldnt make them levels (support->warriorr->builder) either because eventually youll just have a ton of builders, a huge messy castle with everyone destroying something to get more space for new stuff, and some single warrior throwing granades over the walls at the enemy... and nobody wants to play a long time playing roles they dont like.

Alright well as I see where this is going I suppose I should be more specific.

The answers given so far are actually insightful.

I played ultima online for a very long time. That is the best sandbox example I have at the moment for the style I would shoot for. Minecraft is also sandbox and is practically the definition of it except that is not exactly what I am talking about.

I don't want to give the impression that I would be creating a medieval style rpg sandbox mmo. After all the game may not be set in that particular time period at all. It may not even have the type of elements expected. By that I mean it may include objects from multiple time periods or even fictional time periods.

I guess I envision a game that puts players in control of a character within an open world that allows players to choose what they want to be and what they want to do. The fact it is so open is actually what makes the replay value almost infinite. No set story no treadmill questing. I would even go so far as to try to implement a system where players can drive some type of story on their own a system for creating events that playout with various outcomes based on conditions.

I am pretty set on the idea of 2d perspective with 3d modeling. I think more detail can be given to the world under those conditions than can be done in a completely 3d environment currently. Think about the diablo 3 graphics and imagine a thousand times for detail given to it. Things are 3d models but the view is still 2d top down. The difference in detail is not in the artwork but in the amount of objects and environments. The artwork in D3 is already very detailed.

I also think that engaging pvp should be a big part of things. The game would not be something for casual players by any means but that is also part of the end goal. You can either dedicate to becoming good at the game which would take time or move on there wouldn't be any room for casual play until very late game and only if you were to become well enough off in the game to kick back a bit.

Competative with high intensity action would be a good way to describe things. But not revolving around that aspect alone.

This is a more detailed explanation of what I am talking about. I know the subject of a game like this is pretty big so forgive me if i over simplify aspects of it. I just want to keep the conversation managable.

I only ask what the demand is for a game like this as a general reference nothing more.

The demand for any game is there. It just needs to be done right.

You could have a 3d world with a fixed camera to give it a top-down look. You don't need to rely on 2d unless you find a practical purpose for it over 3d.

Determining what makes the game worth creating is more important than whether or not someone would want to play it. The game is to be created, not sold. If all you want is money there are probably much better avenues to earning money.

A descendent of UO with RTS elements added and a world that players actually discover is something I have had in concept mode for a while. The desire for a game like it is there, but it is all in the implementation. One small error in design could break the whole thing.

The demand for any game is there. It just needs to be done right.

You could have a 3d world with a fixed camera to give it a top-down look. You don't need to rely on 2d unless you find a practical purpose for it over 3d.

Determining what makes the game worth creating is more important than whether or not someone would want to play it. The game is to be created, not sold. If all you want is money there are probably much better avenues to earning money.

A descendent of UO with RTS elements added and a world that players actually discover is something I have had in concept mode for a while. The desire for a game like it is there, but it is all in the implementation. One small error in design could break the whole thing.

You misunderstand what I mean by 2d. I am talking about a 3d world in 2d perspective. Meaning it would actually be built using 3d models and textures with a locked overhead view like you said. Rather than being a 2d game built using flat images.

A lot of the design concepts from UO are lost with today's games I think. To this day there are unique aspects that have yet to be used again.

I have no desire to create a new UO I want to kind of make that as clear as possible. If I get to the point of making something it will be wildly different from UO but should still encompass the same general feeling players got from UO if that makes sense.

Anyhow I can't get off of the idea of making this type of game. It has little to do with making money and everything to do with creating a game that people actually enjoy. As if we have never heard that said before eh. In this case I am a gamer who is simply disappointed with games in the current market and I know there are others who have the same sentiment but I am also able to do a great deal of the work towards making a game and because of that I have a pretty strong desire to see this game happen at some point. Even if that means throwing a lot of money at it to make this happen.

There are many ways to secure funding these days. I give only minor thought to that at the moment. Right now I would like to continue research and start laying out some kind of roadmap for the project. Simply jumping in head first without any direction would be foolish. If I can focus on single tasks things will progress and stay on track. So again right now just getting as much information from as many sources as I can before moving forward.

I think that the point of playing with other people should be about playing with other people, not grinding or just fighting npcs.

I think that the point of playing with other people should be about playing with other people, not grinding or just fighting npcs.

Exactly. I feel like the player interaction in games has been lost. Not because players don't want to interact but because developers do not facilitate interaction well at all these days.

I think that the point of playing with other people should be about playing with other people, not grinding or just fighting npcs.

I don't think that should be the main point, but certainly playing with other people should present opportunities to play with other people for players who want to do that.