Well, there have been two instances where i have experienced full on RP, as in, you are your character, all the time, with very few exceptions allowed. You behave like your character would, and straying too far from that could lead to penalties, also metagame knowledge is forbidden and you are forced to react to stuff your character is not supposed to know but you do, as if you didnt.
You need to submit a background for your character, a coherent one with the world you are going to play in, and for that you need to read some documents about the setting, usually very brief.
The first one was in nwn, where i played on serveral persistent worlds, the second one on a browser based game, pretty historically accurate. Anyway, for that to work you need a special kind of crowd playing the game. One where ive seen the kind of Rp that this game would accept was in City of Heroes, where most people roleplayed their character to some degree (varying from normal players of any kind of mmo to people really committed that crafted huge in depth backgrounds of their characters and even spoke in a manner than the hero would).
The kind of crowd this games aims to is adult, mature, educated gamers that can commit to certain compromises if it means their entertainment will be enhanced. so... pretty much MILFs and MIWLF (that W is a wouldnt), by extension their male friends and finally also people interested in doing something more than hunting for 10 wolves, so i dont feel people roleplaying all the time in this game would be much of a stretch.