Primary House Rules

My game is based principally on the rules in Original D&D (1974 white box with the three "little brown books"). I use a few selected things from Supplement-I, namely Thieves, simplified PC hit dice (Thieves get d6), and variable weapon damage (first column only); as well as any new spells, monsters, and magic items that I see fit to use as DM. In addition, I make some mechanical adjustments, mostly interpolating things so we don't have to use table-lookups anymore: smoothing ability score modifiers, attack rolls, saving throws, and thief skills, which I call "Target 20" (see also the article in Dragon #80, "The 5% Principle", by Gygax & Lakofka); a scale of 1" = 5 feet; encumbrance in stone units, a silver-standard economy, and no clerics allowed as PCs. See more detail below.

Attacks (Target 20)

Attacks – as well as saving throws, thief skills, wizard spells known, etc. – are all adjudicated by a simple core mechanic that I call "Target 20". In short, this is accomplished by checking d20 + level + modifiers ≥ 20. For monsters, Hit Dice score is used as "level". For attacks, the AC of the target counts as a "modifier" (i.e., adding in the classic higher-is-worse armor class).

This has been found to have several advantages. (1) Faster to adjudicate in play, (2) Eliminates the need for table look-ups, (3) Requires no new statistical entries for monsters, and (4) Smooths out the rate of improvement for both characters and monsters. In general, it gives the same average results as seen in the original D&D tables (with great accuracy for attacks, and somewhat less so for saves). We might argue that the D&D core system "should have been" this from the beginning, but the original designers were overly accustomed to table-based presentations (which makes sense for more complicated probability distributions, but not fundamentally linear ones as seen in D&D).

For more on the "Target 20" system in particular (including statistical analysis of its fidelity to original D&D), see the official Target 20 home page here. For discussions we've had on the blog about this system, see links one, two, and three. For evidence that Gygax was amenable to smoothed-out combat and saving throw charts, see "The 5% Principle" article from Dragon #80 here. Moreover, in 2018 we learned that in the pre-publication first draft of D&D, before any table was created, this was essentially the basis for how attacks and Armor Class were defined in the first place.

Scale (5 ft, 10 sec)

For standard dungeon combat scale (potentially in conjunction with miniatures), we use distance and time scales of 1" = 5 feet; 1 round = 10 seconds; 1 turn = 1 minute. Note that the 1 turn = 1 minute scale (and rounds of a smaller unit) actually matches the root system in Chainmail (1971), which we find to be more robust. The same year that D&D was published (1974), Gygax & Blume also printed the related Warriors of Mars book, with a man-to-man scale of 1" = 6 feet and 1 turn = 10 seconds; and used that again the next year with Boot Hill. Later, Gygax's system conversion rules expressly said, "BOOT HILL inches equal inches in D&D and AD&D" (Boot Hill 2E p. 31, and similarly AD&D 1E DMG p. 113; both 1979). Holmes Basic D&D also gave a 10-second combat round (1979), which was maintained throughout the Moldvay/Mentzer/Allston (BXCMI) lines. Moldvay Basic used a 5-foot-per-inch distance scale (1981), as did 3rd Edition D&D (2000), along with many other game systems.

The advantages here are: (1) Time factor seems more in scale with how long real-world individual "attacks" take (referencing: boxing, fencing, archery, SCA, etc.). (2) Distance moved using D&D specified per-inch rates is likewise more realistic. (3) Scale matches that of the miniatures used (humans at 25mm or 30mm or so, i.e., close to 1 inch). The fact is, Gygax garbled the issue when he wrote OD&D Vol-3 (redefining a turn = 10 minutes, and round = 1 minute), and then doubled-down in its defense in AD&D; but even he wrote a later column noting the "distortions" in the system, and even uncharacteristically asking "collective pardon" for them (Dragon #15, 1978).

I talk about matters of scale a lot. Here are some posts in particular: one, two, three, four, five, six, seven, eight, nine, ten, eleven.

Encumbrance (Stone Units)

People gripe about encumbrance, but I think it's very easy to fix and adjudicate. It just has to be re-scaled so the numbers being added are a few small, single digit values (just like the rest of the original D&D game system, if you think about it). Setting units in pounds or coins is a terrible misstep, forcing players to look up and add fiddly sums in the tens or hundreds per item carried. What you want is granularity at the level of about 10- or 20-pound units or so.

Coincidentally, there is a real-life unit called the "stone" of 14 pounds that does exactly this job for us and more. Advantages include: (1) Units which are so small they can be remembered and added mentally, (2) Convenience that a character's Strength equates to the heaviest nominal load carried, (3) Imperial units connoting in-theme archaic flavor, and (4) Many tiny items falling out of consideration entirely. You do need to present an encumbrance table converted to units in stone (see first link below), but having done so, it's then exceedingly easy to pick up and use.

Posts where I've discussed the "stone" system of encumbrance valuation: one, two, three, four.

Money (Silver Standard)

Coins in the middle ages weren't usually gold; in general, daily transactions were made with silver coins. Therefore, it makes a lot of sense to interpret all prices as being in silver pieces instead of gold pieces. We still use the conversion rates in OD&D as written (1 gp = 10 sp; 1 sp = 5 cp), but award 1 XP per silver piece of treasure (instead of per gold piece). For treasure in loose coins, you should divide all amounts by 10, so that game balance is the same as that in the books.

Advantages for using a silver-based system include: (1) More traditional flavor to coinage, making gold and large treasure troves something special; (2) Prices are then (surprisingly, perhaps) broadly in tune with historical sources, and we can apply real-life medieval wages and prices to the game; (3) Characters can carry much greater amounts of value (and experience) on their persons, particularly at the higher levels, without resorting to bags of holding and the like.

One other numismatic note: Shillings and pounds were not coins! For example, England regularly used the silver Groat (1/3 shilling) and gold Noble (1/3 pound), and we presume something similar here for our "silver pieces" and "gold pieces". Posts on the preferred money system: one, two, three.

Classes (Clerics Removed)

Sometime around mid-2008  I had an epiphany and realized that I had to discard Clerics from my game. That was an admittedly radical step, but the amount of relief that I immediately felt was intense, and I haven't looked back since. D&D finally "felt right" to me. Now, I treat Thieves (from Sup-I) as a "replacement" for the 3rd core OD&D class slot. The clerical healing function I provide by making potions of healing available for market purchase.

The advantages that I personally find to this approach are so multitudinous that I'm compelled to present them in list form:
  1. Don't have to detail a list of gods before play begins (i.e., avoids DDG-type requirement); can keep gods a mystery or forego them entirely.
  2. Don't have to deal with integrated Christian mythology and institutions (equipment-list crosses, biblical-based spell list, Catholic class level titles, etc.)
  3. Don't have to deal with proliferation of miraculous abilities among clergy in every church in the campaign.
  4. Streamlines the magic system to just one class (wizards).
  5. Avoids many problematic spells (silence 15' radius, know alignment, etc.)
  6. No open-access to entire spell list, thereby avoiding brokenness (becoming overpowered) and plot irregularities when spell lists are expanded.
  7. No turn-undead ability, which turns otherwise fearsome monster types into the most easily defeated ones.
  8. Healing "requirement" is spread across the entire party, not just one player.
  9. Creates an elegant system of one class each using d4/d6/d8 hit dice, none/light/heavy armor, and attacks progression at 2/3/4 levels.
  10. Avoids disassociation with priest/healer archetype that is more generally seen as peaceful, robe-wearing, etc.
  11. Avoids robbing fighters of specialty in wearing heavy armor.
  12. Avoids singularity of the only class unavailable to demihumans or multiclassing in OD&D (or listed as NPC-only in the AD&D PHB).
  13. Avoids oddity of one class type mostly missing from OD&D wandering monster tables.
  14. Matches most pulp fantasy sources in which fighters/thieves/wizards are common, but miraculous warrior clerics are rarely (if ever) seen.
Notable posts where I've discussed the problems with clerics: one, two, three, four, five.