Changes, expansions and additions include:
1. A big change in the original trinity: Thieves replace Clerics. We did this for a number of reasons that I won’t argue for here, but I think it “fit” both with our own goals and the spirit of the original. Zylarthen Thieves are a bit different—simpler in conception, perhaps—than some of the standard offerings, but owe much to the discussions of Thieves and Thief abilities by some of the old school bloggers. In turn, spells are shuffled around, as might be expected. Turning Undead becomes something that any character can theoretically do (with a holy symbol) but that enhances the importance of wisdom (that perennial “dump-stat”). And healing, as well as “surgery” becomes a sort of group activity, as opposed to being relegated to Clerical “medics”.
2. A simple but I think robust mechanic for differentiating weapons in an interesting and meaningful way while for the most part preserving the original conception of all weapons doing the same 1-6 hits of damage.
3. A more “realistic” but also (I hope) simple and playable set of encumbrance rules with the goal of enhancing “resource management” decision-making. The equipment list is somewhat expanded to include additional essential items (and a few whimsical ones) but hopefully avoids the temptation of “item creep”.
4. A different take on treasure and experience points that (hopefully) goes a bit towards “solving” some of the issues involving living expenses and player-characters accumulating “too much” money, as well as creating additional interesting decisions for the players. As with a number of other items, the idea is not completely original but makes liberal use of some of the ideas that have been floating around the old school blogosphere for some time.
5. A relatively unique take on player-character and monster languages that makes knowing extra languages more meaningful while making the question of which monsters speak what more interesting and unpredictable.
6. Enhanced tactical combat options, including rules for doing additional damage, fighting with two weapons, weapon breaks and more, while keeping things as simple and intuitive as possible.
7. Rules for going to negative or (as I call it) zero hit points that preserve the relative lethality of OD&D combat (yes, you very well might die) but that also create some interesting situations and decisions.
8. Greatly expanded content for some of the “lost” or barely mentioned monsters in OD&D such as Amazons, Witches, Vikings, Androids, Martians and others (including gods and goddesses), as well as new or somewhat new takes on a few standard and giant insects and animals. There is also additional detail on potential hirelings, troop types and non-player character parties. These are accompanied by comprehensive and thorough monster level and wilderness encounter tables in the old school style.
9. An original method for creating wilderness maps and expanded or clarified rules for wilderness adventuring, using the (often neglected) suggestions from the third little brown book as a springboard.
Major areas of continuity include:
1. De-emphasizing the “make or break” importance of ability scores (in line with the original edition) and thus offering a relatively small and clear list of potential bonuses and penalties.
2. Drawing the line at three (or six) classes and preserving the “race as class” concept.
3. Preserving the rough outlines of the original level and experience point progressions while offering all new level titles (for both Lawful and Chaotic characters) up to “name” level.
4. Preserving the original “pre-inflation” mechanic of 1d6 damage and 1d6 hit dice for player characters and monsters, along with a general bias against multiple attack routines.
5. Clearly compiling and integrating all or almost all monsters and spells from the first one-and-a-half or so years of the game—with a few twists given the absence of player-character Clerics (there are still non-player character Evil High Priests, of course!) and a small number of semi-new spells for Witches.