Regarding "Avis Durgan", the earliest game I have seen her name appear within the data of is the Time Zone game released in 1982. As far as I know, this was the first game that Jeff worked on. The story I've read somewhere was that Jeff started with the then On-Line Systems in 1981 while the Time Zone project was in development and he immediately joined that project team. This was Hires Adventure #5. It is not surprising then that Hires Adventure #6, i.e. The Dark Crystal, also has "Avis Durgan" in the data. I don't think Jeff is in the credits for that one (Greg Rowland is though) but I assume that they used Jeff's modified version of the ADL interpreter code from Time Zone in the Dark Crystal project.
While The Dark Crystal project team was hard at work, Jeff appears to have been working on other things, one of them being the September 1982 "Adventure in Serenia" release. This was a port of the 1980 Wizard and the Princess game (Hires Adventure #2) for the IBM PC. If we look in the data of that release, we'll also see Avis Durgan in there.
Note that it appears in different forms. Sometimes it is in all caps and joined together, but it is still clearly the same name. So when I say "Avis Durgan" appears, it may not be exactly like that. It might be AVISDURGAN or something similar.
Jeff worked with Chris Iden on the IBM PCJR port of the Wizard and the Princess that came out in 1984 and we can once again see Avis Durgan in that games data.
So when Jeff started refactoring the GAL interpreter code (written by Arthur Abraham, Chuck Tingley, etc.) to create the AGI V1 interpreter code used in KQ2, it isn't surprising that he added the Avis Durgan XOR logic, and from there it seems to have appeared in most AGI games that followed afterward, across the multiple platforms that AGI ran on.
I don't recall anyone mentioning if it appears in the SCI games. Perhaps he chose to stop doing that when he began working on SCI. Still, its an impressive number of Sierra games that he managed to hide that name within.
