Taichara's asked for some input on what people want from an historic setting for RPGs, in her case specifically Red Box D&D. Again, I find myself pressed for time, so instead of writing something pithy and quick for her comments, y'all get a whole blog post. ;p
My chief interest is in how this setting can shake up my game. Whether I'm going to use it as a brief jaunt for a change-of-pace in an existing campaign, or the setting for an entire campaign in itself, I want to know pretty early on how this will be noticeably different (and, hopefully, better) than your bog-standard Middle Earth clone.
This really is the bedrock, from whence all the rest should flow. Who are the folks that live here? What's important to them? Where do their assumptions differ from ours?
Granted, this is the area most likely to be ignored in the heat of a game. Players often bring their cultural baggage to the table, and that's fine. But there's a good chance I'll want to let them play strangers in this strange land. So show me how these folks are different from the people I know. At the very least, let me know what they eat, what they wear, what they love, and what they fear. I'd like to know how they celebrate the stages of life, and if their ideas are different from ours on that score.
Politics would be useful as well. Who wields supreme executive power and upon what mandate? Who is likely to hire the PCs, and what are they likely to want done? Who might try to thwart the PCs? Who's in charge of maintaining law and order, and what are their methods and tools?
If you give me nothing else on their culture, I do want this. How do they measure time? What days are special to them, and how do they celebrate them?
What do the people of this setting worship and how? This is where you can really shine and be useful to the DM, since D&D generally gives you next-to-nothing on playing and adjudicating clerics. Let us know how clerics interact with the temples and the gods. What worldly and organizational resources does the cleric have to draw on? What sort of behavior is likely to get a god's nose out of joint? Does the religion of this setting necessitate changes to the clerical class, or the creation of entirely new classes?
The D&D equipment lists tend to be a bit anemic as it is. Feel free to flesh them out with all sorts of setting-specific goodies.
I'd not go on too long about weapons. Yeah, they can be cool, but D&D's combat is so vague it really can't tell the difference between a viking's broadsword and the pharaoh's khopesh. If it's important, go into metals and materials and how they make a difference, but most things can be mentioned briefly (“they make their shields from woven wicker” or “their helms are fashioned from the tusks of boars fixed to leather caps”) and then you can move on.
You'll probably find it's more interesting, especially for folks who enjoy hex-crawling, to talk about mounts and beasts of burden. Ancient India has elephants, and ancient Egypt will have the camel. Such beasts can make a big difference in combat, logistics, and wilderness exploration.
Normally, I'm not a huge fan of additional magical goodies, but they can be evocative and this is Taichara we're talking about here. ;) If you are going to give us new magical items, make sure they are both new and evocative. A bag of holding with feathers stitched to it is still a bag of holding.
Architecture and Maps
Most historical time-periods have evocative architecture that immediately brings them to mind. The Egyptians, of course, have the pyramids and their great, giant columns in post-and-lintel architecture erected on a grand scale. The Romans had their arches and the Colosseum. The Japanese have their sliding paper walls and nightingale floors. Show us how these things work and give us some context for them.
Give us maps of the homes and shops of the average folk, and at least one tavern, inn or similar place where adventurers are likely to congregate. Maps of temples would be useful, especially if there are competing faiths in this setting. A map of a village or a city where adventures can start or take place wouldn't be a bad idea, either.
Think also about common locations for adventures. Tombs, forts, jails, palaces, temples, houses-of-ill-repute, seedy taverns, and inns are all places where adventurers might practice their trade. Maps are something we don't often see enough of in books like this.
You can do a lot to make a setting feel special by changing the rules for how magic works or creating new magic. One place D&D is historically lacking is in daily-use spells, the sorts of magic people used in their homes or in their work, and yet it's the what we have the most examples of from real history.
Again, normally I'd say don't go crazy here, but we're talking about Taichara, and such things don't apply to her. :D Some creatures just scream to be made over (the mummy, for instance) while some are missing all together. Keep it flavorful and remember that this is D&D, so we don't need giant stat-blocks or great whopping lists of powers.
I'd rather not see amazing re-imaginings of the traditional monsters. The scarab-swarm lamia of 4e, for instance, does nothing for me. I'm quite happy with the traditional monsters as we see them in folklore.
Please include at least one which highlights how adventures in this setting can be different. I'm just as capable as the next guy of replacing the King's daughter with the Pharoah's daughter. Give me something that really highlights, for me and my players, the possibilities of the setting. Give me something that only this setting and no other can deliver.
And heck, if you want to give me a book of adventure locations that, over its pages, reveals a setting to me, that'd be great. It doesn't necessarily have to be a tightly-linked adventure path, but maybe five “locations” that include an introductory adventure, some tomb-like areas to plunder, a city or town that can supply both a base-of-operations as well as adventures in its own right, the headquarters of a powerful antagonist, and maybe a wilderness area suitable for exploring and building a stronghold on.
Finally, steal a page from Monte Cook and do a player's PDF. This should help explain the setting, lay out the basics of the culture and any rules changes the players will need to know to make a character in it. If you're going to spend money on art, it should show up here. Art is a great way to make a setting come alive, and to communicate the style, themes, and feel quickly. If at all possible, it should help the DM sell the setting to the players.