So, when I played through Dragon Age Origins, I encountered the Desire Demon a few times. I got to thinking: What would it be like to create a character that could be a demon of any type you could choose, and aimed to get to the top of the demon's world? It would possibly be one of the more interesting experiences, I think...

This is obviously a "mature content" suggestion, but if there are "succubi" demon types in the Elder Scrolls universe, then perhaps they could be implemented as part of a side story quest to acquire a new companion, or implemented as a new "playable race" in a "New Game Plus" after you've beaten the main game.

Demons are often depicted in a very narrow focus, and it doesn't give the player an opportunity to explore their backgrounds, way of life, etc in any real depth through interaction. These days, they are just viewed as "levers" to advance a plot, or in a more apt description, they're that "random bad guy" for anyone to go kick around.

Also, somewhat unrelated: I can't be arsed to install Oblivion on my PC, even though I have everything ready for a fresh game; the problem is that OBSE requires a lot of stuff to be installed to work properly (including a third party launcher), which means it'd be too tedious to work with. A request for Skyrim: Please avoid implementing limits on scripting in Skyrim! The OBSE for Oblivion was created to help increase the number of executable scripts with different functions, I feel that Skyrim should at least implement what OBSE brought to the table for Oblivion, so that there are infinite modding capabilities.

I sort of know a thing or two about this subject and I must say that when video games attempt to put "demons" in them they usually butcher the experience for me. Few games have done them even half way properly, and even fewer do enough research to understand where the word comes from and what it really means.

I would really not like to see Elder Scrolls try to implement this idea of "demon" in their game anymore than they already have with the Daedra, which surprisingly isn't that poorly implemented by relation.

When video game designers who haven't read more than 1 book in the last 12 months and are surrounded by friends and people who don't know what they are talking about try to implement something like this it ends up sounding like some kind of urban legend drivel that a 10 year old boy wrote. It is best to hire real writers and to make sure that you fully understand all of the variables involved in bringing something like this into the game including etymology and the various origins of the meaning behind it.

Oddly enough there is at least one mod that has made a desire daemon for Oblivion.
I know the maker / s have posted on Lady Moiraines site, and more than likely in Nexus.

As to would I like to play as one, modded I already have.
I have run, and am planning on running again a Retcon of Fall from Grace from Planescape: Torment.
Using RBP and other mods if I get round to it.

For a vanilla game, my answer would be a cautious maybe.
Like Seven Dragons posted it requires good creative teams dedicated solely to implement a new race or function to lore and the games universe.
Then you have to account for peoples imagination, too much infomation could hinder serious role players.
Not enough makes those that want to know every detail frustrated.
Then you have to figure out how powerful they should be, offset this with weaknesses, how would churches and faiths react to them, let alone your average Joe.

Honestly for TeS, if they make a game that starts and is focused on a Daedric realm it could work, for Skyrim not so much..

However I'll post this again, I wish someone would buy the rights to Planescape and make a decent open plane game set in those universes.
As then you'll be able to play as whatever you wish.

i played the dremora mods for both morrowind and oblivion and i played the predator mod (two thumbs up) for morrowind. theres one for oblivion but i never got around to trying it out. the only game recently that i have played that let you play as a demon was dark messiah and a SNES game called 7th Saga. they are fun but since your characters are a bit OP i usually get bored with them. i prefer characters with flaws and disadvantages.