Fallout 2: I've heard a dozen times that he was the main narrative designer. False.
Planescape: Had 4 writers. Colin Mccomb arguably did more than Avellone. Gets no credit.
Mask of the Betrayer: Was George Ziets brainchild. People still claim it was Avellones.
POE1: Durance is the most praised companion. Nobody mentions he had two writers.
Tyranny: Everyone claims he personally designed the world and lore. He admits that he barely did anything, and it was all someone else's ideas from a decade ago.
Kingmaker (psychic abilities): Avellone is praised as writing everything himself, when in reality he only wrote a few NPCs and a companion.