New classes

[AxeMental]

I believe Gygax encourages DMs to create magic items, and even to create new monster types (someplace in the DMG I believe it states or suggests this). But does anyone know if Gygax envisioned DMs creating new classes for players to take? Is this stated anyplace in the DMG for instance? From Dragon Mag, I get the impression that Gygax would have been very open to this idea (look at all the goofball ideas Dragon threw out there over the years). But then again, Dragon was a product that needed to be sold to make money, and in that case Gygax might have been supportive to meet the bottom line. I do recall some saying that EGG was worried about drift in 0E and hence created a more solidified and complete 1E (so that each table was pretty much on the same page).

My guess is that he wouldn't have approved early on, but that position would have changed by UA.

[sepulchre]

On the one hand, judging his work on the Greyhawk and demi-human clerics in the Glossography (some of that reprinted in U.A) I believe he favored tweaking the basic classes (in this case the cleric): clerics who are devoted to the god of death may achieve 1 lvl. as an assassin for every 3 as a cleric etc. In some cases this is expressed as an experience point penalty of 10%/lvl while in other instances the cleric is not penalized in anyway.

Certainly, he favored subclasses too, but I doubt he would have supported moving beyond the basic four classes in AD&D.

[rogatny]

I think this is one of those cases where we have to remember Gygax's distinction between "D&D" and "AD&D." I think as the standardized version of the rules, "AD&D" is a much smaller subset of "D&D" and that to be "AD&D" to Gygax, it should contain all those things not explicitly labeled as optional in the PHB. It could however contain additional things beyond what was in the PHB and still be "AD&D."

Thus, if you remove all the sub classes (optional) and add a few of your own subclass, you're still playing "AD&D." If you've changed the cleric to a scientist, removed the thief, and completely altered the magic-user's spell casting system, you've probably left "AD&D" and have entered the realm of "D&D."