Originally, most Campaign Settings in Nolaria used the AD&D2 rules system, although (technically) very early games were run using the original D&D rules set and later under Advanced D&D. Rules that govern these earlier games are documented in the AD&D2 books and the Erebus Players Handbook (copies provided on request).
Recent games (2018 and onward) have used the D&D Fifth Edition rules (5e). These games are run using the 5e Player's Handbook (PH), the Dungeon Master Guide (DMG), Xanathar's Guide to Everything (XGE), and various monster books (Monster Manual, etc). There are two main issues with using the 5e rules set for Nolaria:
There are many optional rules.
Rules need to be adjusted to maintain the "flavor" of Nolaria.
By default, all optional rules are NOT in play unless otherwise noted. Please see the Optional Rules page for a more complete status on optional rules. All rules, extensions, etc. from the Sword Coast Adventurer's Guide are not allowed or in play as it pertains to a world beyond Nolaria.
The issue of maintaining the flavor of Nolaria is a more difficult thing. Many societies in various parts of Nolaria depend heavily on magic. The magic system described by the 5e rules is not quite the same as it is in Nolaria. For example, the written form of magic is based on Cabbalism, which is not even defined in 5e which instead relies on the "weave of magic". Since cabbalism is also the basis for almost all magic items, this becomes a serious conflict with the way things are described in 5e. Some (hopefully most) of these issues are modified by the interpretations found in this section. Be patient, this is a work in progress.
I also have issues with the 5e combat system. Taken as a whole, the 5e system is ALL about combat. It is an essential part of the game, whereas in older Nolaria games it played an important role, but there was a lot more to playing a good game. Some of the imbalances in the 5e combat system are well known, such as the imbalances introduced by the Action Economy. Other aspects such as moving through occupied spaces, friendly fire of ranged attacks, facing, etc. needed to be modified to preserve some feeling of how combat used to be done. These interpretations are also included in the pages below.
Nolaria is a rather typical Material Plane of Existence, but it is set in the context of the larger multiverse. I use the older definitions of the various planes: inner, outer, etc. Play sometimes occurs in these other planes, including:
The Outlands - center of the Great Wheel
Sigil - the city of doors.
Planes of the Blood War
Astral
Elemental planes of earth, air, fire, and water.
Some of the quasi-elemental planes.
Special planes such as the Omitican and Shadowfells