First of all, let me apologize for having been so quiet. It's been a hard year and gaming has taken a secondary priority for me. Hopefully, I can concentrate on it more going forward. Secondly, I do want to get back to the series examining the "endgame" in AD&D, but that will have to wait.
Right now, I want to discuss something that not many people pay attention to, which is how AD&D can be adapted to different settings. If a setting is just a "Dungeons & Dragons" setting, then this isn't really as necessary. There are many similarities between Oerth (World of Greyhawk) and Toril (Forgotten Realms), as well as Mystara (the Known World of the Dungeons & Dragons line), and only a few small differences. Any number of other settings are similar in tone as well. But there are some settings which have a very different feel to them. Krynn (Dragonlance) is not much like the aforementioned settings, nor are Athas (Dark Sun), Aebrynis (Birthright), or, at least in general, the Crystal Spheres of Spelljammer. Looking to other companies' products, the lizardfolk-inhabited continents of Torsh in Judges' Guild's Portals of Torsh are specifically engineered to be like a dinosaur-filled Lost World, while the other worlds of the "Portals" line (Portals of Irontooth and Portals of Twilight) have their own distinct themes, tones, and feels. But enough of examples. We're here to examine what a DM has to do to create a specific tone and feeling for their setting. It's worth noting that games like GURPS are explicitly built around taking these steps, so a lot of these ideas come from there. One of GURPS's worst weaknesses is that it doesn't provide much of a place to start from like AD&D does. Everything has to be built by the Referee from scratch.
First of all, the DM is well-advised to go through and adjust the creatures in the Monster Manual, and perhaps the Fiend Folio, Deities & Demigods/Legends & Lore/Manual of the Planes, and Monster Manual II. A great deal of the tone of the setting comes from the sorts of entities that the players' characters might encounter. First of all, ruthlessly eradicate any entry that doesn't fit the setting. If the setting doesn't support having a variety of humanoids, eliminate the ones that don't fit. Perhaps the only humanoids around are Goblins, or maybe the whole line of Goblinoids—Goblins, Hobgoblins, Bugbears, and perhaps Kobolds—are present, but not Orcs or Gnolls. Or perhaps Gnolls and Flinds are present but not any of the others. Similarly, evaluate the demihumans—maybe there are Dwarves and Gnomes, and both are called "Elves" by the people of your setting, but there are no Elves as AD&D specifies them. Maybe you have another demihuman lineage in your setting, such as the Uldra found in Dragon magazine issue 119 or the Winged Folk of issue 51. Do you have Giants? Titans? Psionic monsters like Mind Flayers? Significantly, too, you will want to consider the various types of Men that can be found roaming your setting, and particularly the makeup of groups that might be encountered.
Next, once you've culled the creatures that don't fit the setting, find the ones that are different. Perhaps your Ghosts aren't uniformly Evil, and maybe their magical attacks aren't involved with aging. Perhaps you prefer to reskin the undead spirits found in the monster section of Oriental Adventures so that Evil ghosts use the description of the Gaki. What if you want Vampires in your setting to be more like those in Anne Rice's Vampire Chronicles, or the ones in Stephanie Meyer's Twilight Saga for whatever reason. Those will require a rewrite in such cases. You will have to do these things for every entry in the monster catalogs, adding in your new entries and adjusting the old ones.
Once you've gone through that step, it's time to create new random encounter tables. I suggest using the ones in the DMG as a model, at least for the wilderness encounter tables, then adding additional tables specific to various regions of your setting, similar to the ones in the World of Greyhawk "gold box", that act to replace the checks for Patrols found on page 182 of the DMG. As for random castles, that's really up to the DM to include or not, depending on how detailed their maps for the region are. Personally, I prefer to have more control over settled defenses like that, but am perfectly fine with random encounters dictating the movements of nomadic or other rootless groups like Pilgrims. This may be the most work-intensive step involved, but it's an important one as it will dictate the frequency of various encounters. If your setting has more or fewer Fae-type creatures in an area, for example, then the players' characters should encounter them more or less often in any given encounter. A setting where most of the dangerous encounters are with bears and moose will have a different feel to one where Ankhegs suddenly burst out of the ground and Griffons regularly stoop on the party's horses.
Once the creatures of the setting are tuned to fit, it's time to work through the options the players will have. Perhaps your setting has only two types of player characters: Fighting Men and Magic Users, or maybe there will be a third sort of character who specializes in non-combative activities similar to Thieves. Or maybe there's a wide variety of character classes in your setting, such as versions of the Warlock, Sorcerer, or the Sha'ir from the Al-Qadim setting of the AD&D 2nd Edition supplements (as an aside, Jeremy Reaban has a bunch of character classes written up for AD&D, OD&D, and the D&D line over at DriveThru, all priced as "Pay What You Want" at this time, including a couple of reworkings of the Thief intended to fix problems he perceives in the class; if you hunt through the "character class" label on this blog you'll find a few others that I've designed or adapted from other sources as well, though also some dead ends of thinking toward an OSR-style SF game and some general discussion of the idea). At this point, you'll also want to be thinking about whether or not there are Psionic powers in your game, though you could also have thought of that while curating your creature lists. Other powers, such as the powers of the "Dreamer" semiclass found in Dragon magazine issue 132 or the Bloodlines found in the Birthright setting, might also come up for consideration. Perhaps you want to adapt the Kai monks and the Magnakai from the Lone Wolf series of solo adventure books. Whether you use Nonweapon Proficiencies found in Oriental Adventures and the Survival Guides or Secondary Skills from the DMG page 12, or perhaps a different system such as the one described in Savage Swords of Athanor (more discussion and resources can be found at this abandoned blog) will also have an effect on how your setting will feel, though a more subtle one perhaps.
Next, consider changing elements like Alignment. Perhaps you want to replace a generic "Law" with specific regions, governments, or individuals to whom loyalty might be owed. Maybe your definition of "Evil" and "Good" is different than the default assumption of treating Life as sacred or not. This can also have direct impact on the setting, such as a different cosmological structure than the "Wheel" cosmology laid out in the PH, DDG, and Manual of the Planes. Maybe you'll simply redefine "Evil" and "Good", for the purposes of spells, as whether or not something comes from the Invisible World or from the Perceptible World. Maybe your cosmological structure is derived from the Kabbalistic Tree of Life, or from the Aeonology of Simonianism, or even something more abstruse like the Books of Jeu and the Pistis Sophia, among many other similar schemes found around the world. Does your setting have Nine Worlds like those found in the branches of Yggdrasil? Maybe mysterious Otherworlds are found across the sea, like the magical islands found in Irish literature.
Another area to consider is the available technologies. If your setting is Bronze Age, it will have different types of armor than a High Medieval setting, while some settings will have gunpowder and others will have airships floating along trade routes across the world. At this point you should also decide on your system or systems of coinage, whether you want to redefine the weights of various weapons to be more accurate to history, and perhaps if you want to adjust the various other attributes applied to weapons such as damage, weapon vs. armor type adjustments, and so on, or indeed whether to eliminate some of the more fiddly bits.
Anyway, this should give you some suggestions of places to look to make your setting different than all of the others to be found out there.
