Just came across this in Polyhedron 80.
In the expansion for the old SSI game, the Shattered Lands, there was an expansion called ‘the Grey Isles’. This introduced the Grey Isles area of Athas. The Grey Isles are ruled or controlled by Athasian doppelgangers, which are supposedly more powerful than doppelgangers on other worlds.
This is the first and only time I’ve ever heard of this. The Grey Isles sound fascinating and Athasian Doppelgangers seem pretty nasty from their description. Makes you wonder whether Rajaat ever became aware of them or not and whether he ever assigned a Champion to their demise (I’m seeing a Champion falling, a doppelganger replacement and all kinds of merry hell being wreaked during the Cleansing Wars by doppelganger assassins). Pity it was never followed up in DS print 
I want to clarify that I can’t find any evidence that the Grey Isles was actually ever released.
Hold on a minute -
This might be it.
https://lparchive.org/ADD-Dark-Sun-Shattered-Lands/Update%2028/
And this advertising for the Grey Isles.
We know the races on Athas aren’t the same as other settings. Trolls, for instance, are a lot like Goliaths, for instance.
I always planned on the ogres being doppelgängers, essentially. The high ogres from dragon lance (“irda”) are beautiful shapeshifters, and that’s what I was going to use as the “ogres” of athas in a green age setting.
As for the SSI games, you can get them on good old games for cheap. My credit union refuses to do business with them, however, so I’m out of luck (think GOG is based out of Malta, and my CU just literally won’t do business with any entities in Malta).
In a galaxy far far away named WotC Forums we used to speculate on the lost races, those either wiped out or that just aren’t found in the Tyr Region (the Heartlands). We made Champions for them.
Barien, Mindflayer Dessicator
Pennarin, Doppelganger Eradicator
Pennarin, I remember you from the WotC forums.
The forums were full of vicious debate about canon. The debate was vicious because the stakes were so low. LOL.
I vaguely recall those conversations when I lurked on the WotC forums. Pennarin was the creation of Lynn Abbey from RaFoaDK - he got obliterated by Rajaat during the Revolt IIRC.
Did the Wizards forums decide whether Barien and Pennarin succeeded in eradicating their races?
Since there was no magical Highlander-There-Can-Only-Be-One thing that happens when a race got wiped, at least one Champion who thought he had succeeded failed and didn’t know better
No one had decided. Mindflayers existed in my web project, and Doppelgangers could easily still do, considering there even were player character races, iirc from Eberron
The info contained in the images is a definite product of the 90s, to say it politely. I do like the “Athasian doppelgangers are more dangerous and terrifying” than in other worlds. Feeding on emotions? The Zhackal already does that, so precedent. This would also make them psionic, a plus.
And yes, there was some level of toxicity on the WotC Forums, it was a different time.
Just make them dread doppelgangers like those in Ravenloft and fluff their abilities as psionic.
http://www.fraternityofshadows.com/Library/VRSDoppelganger.zip
redking, the document is blank starting page 69
Pennarin,
It works just fine for me. Download again, and use 7zip to open it.
Worked. It’s a cool document. Very Ravenloft (which I don’t like), clearly a labor of love to centralize so much lore from multiple editions, plus the new 5e mechanics
