Wednesday, March 14, 2007

OD&D Variant Rules

One of the wonderful things about the OD&D rules (addictive, even) is that they're sparse enough to be manageable if you're interested in modifying, house-ruling, or fixing them. For example, when I think about modifying 3rd Ed., such as its skills or feats system, I find that there are simply far too many entangled parts to spend time modifying the entire game system. Below you'll see some very simple modifications to the OD&D rules that I think provide huge benefits. In particular, I've always been frustrated by D&D's ahistorical gold-based economy; you'll see that in the course of a single evening I was able to complete an analysis and change the entire pricing structure of all the equipment, wages, treasure, and constructions in the entire game to largely fix that!

The alternate damage and hit die system from Greyhawk (Supplement I) is not used. The majority of weapons still do 1d6 damage, with the following exceptions:

* Dagger, Hand Axe, Mace – 1d4 damage.
* Halberd, Two-Handed Sword – 1d8 damage.

Two-handed weapons are as follows: Pole Arm, Halberd, Pike, Two-Handed Sword, Spear.

Throwing weapons are the following: Hand Axe, Spear (3" range each, no modifier to hit from range).

Other missile weapons have the following ranges (from Chainmail): short bow 15", crossbow 18", longbow 21", heavy crossbow 24".

An alternative combat system is presented here that produces nearly the same results as the book, but is so simple that it can be easily memorized without any table references.

For miniature usage, convert all underground scales to 1" = 5 ft (thereby matching ground to standard figure scale). Assume that one combat round takes 10 seconds.

Attacks are made by rolling d20 + fighter level + target AC. If the result is 20 or more, a hit has been scored. Monsters use their hit dice for level; magic-users and clerics use half their level.

Saves are also made by rolling d20 + level + modifiers. If the result is 20 or more, the save is successful. The following modifiers are used:

Fighters: no modifier.
Clerics: +1 to all saves.
Wizards: +1 versus spells but –1 to all others.

Spell: no modifier.
Breath: +1
Stone: +2
Wand: +3
Death: +4

The actual medieval world widely utilized coinage based on small silver-copper-zinc pence (pennies, d). Recognized units were 12 pence = 1 shilling (s), and 20 shillings = 1 pound (L), but these were counting units only, and usually did not exist as actual coins. For purposes of our D&D campaign, we'll assume the existence of large silver (shilling) and gold (pound) coins.

Prices in the game should now generally be read in "pence" instead of "gold pieces". Starting wealth, basic equipment prices, magic item costs, magical research, gem and jewelry values, stronghold constructions, and specialist wages are all approximately correct if read as pence. Exceptions are as follows.

Armor and horse costs should be read in silver shillings (making them much more valuable than other items in the list). Costs for men-at-arms must be read in pence-per-day. Monster treasure tables are read in 1000's of copper, 100's of silver, and 10's of gold pieces (which still results in treasure more than twice as valuable as before). Dungeon treasures should be read in copper and silver pieces, with coin amounts divided by 10 (which results in the same values as before; feel free to exchange amounts for gold on deeper levels).

Note that armor and horses are now so valuable that they are likely out of the price range for new characters. Consider giving fighter-types a free suit of leather armor to start with (much as wizards begin with a free spellbook). All listed equipment costs are for the most basic utilitarian type; finely-made arms and armor, champion horses, quality wines, and even covered wagons will be many times more expensive. Lawful characters should expect to send wealth from a fallen comrade back to their given family, clan, or fraternal order.

I've carefully compared the basic equipment list prices to real-life prices from the Medieval Sourcebook (link below). In general, the prices would be approximately accurate if the were priced in copper pence instead of "gold pieces".

This is verifiable for things like weapons (real-life 6d cheap sword vs. 10 cost in D&D; 5d axe vs. 3; 4d chisel vs. 3-cost dagger), food (a week of dried fruit 28d vs. iron ration 15; a week of cheese, 7d, or salted fish, 2d, vs. standard rations 5), and travel (iron-bound cart 4s=48d vs 100; a barge 10L=2400d vs. small merchant ship 5000).

The notable exceptions are armor and horses, where the prices would be approximately correct if they were in silver shillings; that is, in units 12 times more valuable than other costs.

This can be verified with somewhat more difficulty than the preceding categories (consider real-life 16th c. cuirass with pauldrons, 40s vs. D&D "plate mail" 50; 13th c. merchant's armor for 5s vs. "leather" 15; ox 13s vs. mule 20; draft horse 10-20s vs. 30; high-grade riding horse 10L=200s vs. light horse 40; knight's horse 5L=100s vs. medium warhorse 100).

Similar very rough comparisons have been made using the Medieval Sourcebook's sections for Wages, Buildings (constructions), and Miscellaneous items (jewelry).

The Medieval Sourcebook (accessed March 14, 2007):


  1. Be very careful using that Source Book to find prices for Medieval items. Currency was rarely equivalent and the cost of something in France during the Fourteenth Century can vary wildly from the cost of something in England at the same time.

    If you can get hold of a copy, Fief [] has a much more comprehensive listing and specifies the locality from which the price was derived.

    It is also worth noting that the Medieval Pound used Troy measurements, which makes it around 360-370g, as opposed to the 450g of current usage. A lb was literally the weight of 240 Silver Coins (1.5g x 240 or thereabouts), whilst a Shilling was the value of a similarly weighted Gold Coin to Silver [i.e. 1 Gold Coin = 12 Silver Coins].

    Of course, there was considerable variance and this ratio was only theoretical, as most Gold Coins seem to have weighed 4-4.5g (Fatamid Dinar or Byzantine Besant], which is about three times the weight of a Frankish Silver Penny

  2. The Target20 rule variant is interesting and I will be using it for an upcoming game of Astonishing Swordsmen and Sorcerers of Hyperborea.


    1. Ronald, that's great, I hope it works well for you! Definitely my favorite way to run the game these days.