If you do intend to sell such a game, I think you're going to have a lot of problems earning a profit on it. And I really don't think any publishers would pick up on such a title, knowing that the market interest in such a game would be quite low. Imagine how hard it would be to sell a game the revolved around making Big Macs or mopping floors all day. People generally "play a game" to escape the real world, to immerse themselves in adventure and go on a journey that's normally out of their grasp.
Do you mean to say that Farmville, Harvest Moon, Skyrim, The Sims, Dwarf Fortress, Minecraft, and MMOs in the vein of Ultima Online have this market completely saturated? I think there could still be enough lee-way to atleast warrant a try. You just have to put some new spins on the mechanics, like how battles work, how farming works, how crafting works, etc. It can't be obtuse for new players to learn, but if it works basicly the same as elements of the previously mentioned games then more experienced players won't have as much incentive to add another 'limitless' game to their schedules.
I think this previous post of mine might help get some ideas going (from: http://www.gamedev.net/topic/624851-unextraordinary-you-are-no-one-special-%e2%80%93-an-rpg/page__st__20 ):
In Dwarf Fortress, you are kind of ordinary in rouge-like mode. I say kind-of because I put a lot of skill in swordplay and maybe dodging (?) and ended up having about 13 people come at me before I began to die (there are a ton of injury description stages before anything dies in that game; before-hand I had killed about 4 people without anyone able to hit me even through the beginning of the town chasing after me, needless to say all the injury descriptions made me wonder how any of us were still able to swing weapons at each other... hmmm).
As far as your game, would there be some kind of story or set of game-goals to win or would it be a run out of new stuff to do type of game (like Alternate Reality, played by The CRPG Addict. I agree with him that a CRPG not having a definitive goal to accomplish can be off-putting)?
I think I would like to see a combat system that focuses on avoiding getting hit by an enemy (blocking attacks, staying out of their attack patterns, etc.) and using objects and the environment as a means of fighting. If my character's going to be an everyman like me, but in a fantasy world, he may be adventurous enough to get into a fight, but he will not want to get hit. Therefore, he will always be keeping his distance, getting that sheild always between the enemy and his body, stay behind/on top of stuff, and throwing/whacking with everything that isn't too unwieldy/bolted down. I find such a combat not only hilarious but also communicating just how human and concerned with his/er well-being my character is. If there is a party, there should also be sets of moves that allow for tactics to prevent other party members from being hit and/or becoming frightened (maybe some battles just make 1 or 2 of your party members run off because they fear some enemy far too much or they do not wish to be caught in the fray, and you will have to change up the tactics you were planning to use for most of that area's encounters).
So, any thoughts? Has that last part been implemented in any way in a game (because that would be awesome, and I would appreciate the name and where to get it)?
I hope you make this game you set out to make. Cheers.