So you mean Paranoia without the crazy?
I've always thought of Paranoia more as a horror game than a wacky comedy. So in that context, I'd probably want to keep some degree of the crazy. As in having the ruler/rulers of the kaer slowly go from benevolent town elders to something more controlling and paranoid... a bit of Stalin, a bit of Kafka... a bit of Torquemada. Rebel factions, people who don't believe there is a real threat outside, people who don't believe there is an outside, people who've come to worship the horrors... so yeah, lots of crazy.
I'm not stuck on the Earthdawn aspect so much, just as the genesis of the setting.
I'm figuring it would play out as a bit of nightmare till the maybe PCs maybe come up against the elders... and either take control or are made 'eternal scouts; and have to go look around outside... and then we'll see.
I'll have to have a look at Lost City, I don't know that one. Metamorphosis Alpha crossed my mind... but I assume it was too high-tech/low magic for what I'm thinking.