Mate, I think it's a VERY exciting idea.
The gerbil in my head is furiously spinning his wheel...
What do you think?
I see it as more "Night of the Living Dead" plus any good Apocalypse/End of the World set-up with a little "30 Days of Night" inital concept tossed in. The setting would be less "friendlier" then most setting, lots of running in fear and hiding. Basically a Zombie Apocalyspe with more intelligent undead creature running the "show" who are NOT tommented by their evil side, they actually like being evil. Undead are the bad guys always.I think edbonny's revelation just trumped whatever I could come up with.
Your ideas are a start. I think the perpetual dusk thing is mandatory, and the gladiator pit thing is maybe one image out of countless. Undead and the living shouldn't be so categorised in a setting like this - isn't one of the themes of Ravenloft that the undead are people too?
Undead are the bad guys always.
That is true, but it is kind of hard to be the hero all the time if you are outnumbered and always on the run from you opponents. Eventually someone is goint to get you. Or someone you love.I agree but that doesn't necessarily mean that the living are always victims.
Ascribing power roles by race/undeath-status limits the kinds of games you can play in a setting.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.