Games Workshop offers the core rules for its Age of Sigmar Rules free for the downloading.
The Siege of Minas Tirith is one of the epic battles in literary history. Here’s an entire page dedicated to gaming Tolkien’s Lord of the Rings battle, including photos, terrain suggestions and rules. It’s a major work.
For me, nothing has ever quite caught the magic of the original Dungeons and Dragons rules I picked up sometime in the 1970s. It was a single 8 1/2 x 11 blue book, and it covered only levels 1-5 or so. But it was indescribably wonderful.
Swords and Wizardry is another (I’ve seen several) attempt to recapture that magic that we had before we all became older and White Wolf cynical. The authors write:
In 1974, Gary Gygax (1938-2008) wrote the world’s first fantasy role-playing game, a simple and very flexible set of rules that launched an entirely new genre of gaming. In 1976, the first supplement to these rules was published, with Rob Kuntz as Mr. Gygax’s co-author. Many years later, in the year 2000, Wizards of the Coast allowed the use of most of the material from that game under a license called the Open Game License. What you’re reading is an approximate re-creation of the Gary Gygax original fantasy role-playing game, created using the Open Game License. The re-creation isn’t exact — it’s not allowed to be, and we have treated the original copyright with utmost respect. But while the language in this book may be a little bit less magical than in the original, we believe the rules and system are close enough to reproduce the “lightning in a bottle” of that original edition (often called 0e). In fact, we think Swords & Wizardry is actually a bit better organized and easier to learn than the original. Since the original rules were supplemented with several later books, it’s impossible to nail down any “canon” set of rules for 0e. This is our interpretation of the game, using rules and systems from only the original set of rulebooks and some selected rules-material from the later supplements.
Mobius is a set of free wargames rules for game set in the universe of Archie Comics’ Sonic The Hedgehog series.
Djarhun is a Talisman-like board game free for the downloading. This is a major piece of work with a full color board, and cards.