There is evidence that indicates that OD&D was probably designed to stop somewhere in the level 10-12 range or so. "Name level" (the point where levels no longer get cool names) ends at L8 for clerics, L9 for fighters, and L11 for magic-users. In WARRIORS OF MARS (Barsoom miniatures rules by Gygax in that same general era of game development) only John Carter is allowed to advance to L13. So I'd say that your general premise is correct.Tizun Thane wrote:Wasn't ad&d initially built for around 10th level?
I know you have the spell charts depicting casters up to 20th, but wasn't 9th/10th suggested as 'end game' territory?
One incorrect detail is that you specified AD&D instead of OD&D. AD&D was designed to go all the way to 20th level and I've seen no indication that the upper levels were intended as NPC-only levels, except for the fact that AD&D was based on OD&D+supplements so I suppose you could build a case that AD&D's level ranges were supposed to be similar to those in OD&D. Except that I think a lot of AD&D modules were rated for a party of 12th level characters.
Anyway, someone better versed in AD&D could probably chime in and let me know if my brain is misfiring on this....