Beyond the hero-based gameplay we have had the pleasure of experiencing since Arena, I have been wondering what it would be like to play an Elder Scrolls game based on "the enemy". Sure, DG brought this in a sense (VL's and updated werewolf play) but what I envision is beginning as a lowly Daedra in service to their Prince in an Oblivion realm.
Character creation would let you start as one of several Daedra that have access to various abilities (much like different races do now) and grow (possibly changing form along the way) based on service to your Daedric Prince. Such a story could easily incorporate similar mechanics to current gameplay (ie-equipment, skill progression, etc). At some point in the quest your travels could finally take you to Tamriel to further serve your Prince's needs. It could be very intriguing to base this kind of story on an Elder Scroll prophecy, with the exception that this time.. Oblivion actually succeeds in some fashion.
Some (very) basic outline:
1) character creation could allow you to begin as a Dremora Caitiff (choosing looks/innate abilities/etc). As you complete quests, your rank increases and you gain further favor of your Daedric Prince. (side note: maintaining side questing and exploration. Obviously a must!)
2) introduce magic schools that operate wholly in Oblivion in addition to common Tamriel schools (which may have alternate effects in your home realm as well).
3) perhaps include quests for the Nine Divines in some fashion, much like current Daedric quests.
4) camios from previous characters. Perhaps encountering the Neravarine in an outer realm?
5) discovering more about the deeper lore concerning creation and Mundus.
Just basic thoughts. Anyone who cares to expound on this, please feel free! I'd love input