Publishing your own materials

Swords & Wizardry is all Open Game Content under the terms of Wizards of the Coast’s Open Game License version 1.0a, with the exception of artwork and the trademarks “Mythmere Games,” “Swords & Wizardry,” and “S&W.”

What does it mean that this game is Open Game Content?

It means you can (basically) copy whatever parts of it you want, add your own content, change the content around, and publish the result. You have to comply with the terms of the Open Game License, which is reproduced below. If you don’t care about mentioning any of the game’s trademarks, that’s all you have to do.

Also, under certain conditions, you can even use the Swords & Wizardry trademarks (S&W and Swords & Wizardry) to indicate that your work is compatible with the game. As long as you follow the requirements, you can state that your resource “is compatible with the rules of Swords & Wizardry” or, “with the Swords & Wizardry rules” or, “with the Swords & Wizardry game.” Here are those requirements:

The Swords & Wizardry Compatibility-Statement License (CSL)

You must state on the first page where you mention S&W that “Swords & Wizardry, S&W, and Mythmere Games are the trademarks of Matthew J. Finch,” and that you are not affiliated with Matthew J. Finch or Mythmere Games™.
You must, when referring to the armour class of any creature or character, include both the descending AC and the Ascending System AC, with the Ascending System AC in brackets.
If you’re using the license to commit legal fraud, you forfeit the right to continue using the license: specifically, if you are claiming compatibility with the rules of S&W, the claim must not constitute legal fraud, or fraud in the inducement, under the laws of the State of Texas. Note that this requirement is almost impossible to violate unintentionally—it’s largely intended to keep me out of trouble, not to restrict legitimate statements of compatibility.
You must comply with the terms of the OGL if the terms apply.
Your cover must include the words “House Rules” or “Variant Rules” near the title if the document is a full, free-standing game that includes modifications. Feel free to contact the author if you wish to use a different form of disclaimer.
Selling a full version of this game with your house rules incorporated into it is perfectly permissible, but you may not sell an effectively unchanged copy of the rules for money.
If your document is a private house rules document, not being sold for profit or general use, you may scan and use artwork (including the cover) from the printed version, provided that the cover contains the words “House Rules,” near the title, and that the artists are appropriately credited.
Your rights under this CSL cannot be revoked, and are perpetual, unless you breach the terms of the license, in which case your rights terminate.
If you comply with the above, you may state that your resource is “compatible with the core rules of Swords & Wizardry” or “with the Swords & Wizardry Core Rules.”

If you have questions about the license, feel free to contact the author.

open game content

Open Game Content may only be Used under and in terms of the Open Game License Version 1.0a (OGL).

This entire work is designated as Open Game Content under the OGL, with the exception of the trademarks “Swords & Wizardry,” “S&W,” and “Mythmere Games,” and with the exception of all artwork. These trademarks, and the Trade Dress of this work (font, layout, style of artwork, etc.) are reserved as Product Identity.