>>I did some looking around, and apparently Earthdawn was already a
>>prequel to Shadowrun, taking place the last time magic overwhelmed
>>Earth in the time of Atlantis. It's just that the Bad End of
>>Dragonfall means you've condemned Earth to it a SECOND time.
>
>It's been a while since I played Earthdawn, but I seem to
>recall part of the lore is that a Horror Overrun eventually happens in
>every era. So you basically just kicked off the Sixth World's a bit
>early.

This is what I remember too. I've never played Earthdawn myself, but I was in a long-running Shadowrun campaign that was set in Tir Tairngire (that's the elven nation that took over Oregon). There's a bunch of official backstory for the elven nations that has to do with how a handful of elves are genuinely immortal, have survived since the Earthdawn era (or, in at least two cases, the magical era before Earthdawn) and their high-handed dictatorial rule, scheming, rivalry with the dragons, etc. etc. is all about preparing as quickly as possible for what they know is coming.