Saturday, June 25, 2011

Labyrinth Lord and d% Mechanics

I have been stocking portions of The Tower of Death, my OSRCon adventure, using the standard Labyrinth Lord Revised Dungeon Stocking Tables (LL p. 124). Not normally one to get too "hung up" on rules mechanics, I have nevertheless noticed -- perhaps because I am concurrently reading the LotfP Grindhouse Edition Rules and Magic book -- that Dan Proctor may have a penchant for d%-based tables that is not shared by other out-of-print and OSR-produced iterations of the D&D game.

Take, for example, the "Losing Direction" Table on p. 46 of LL. As you can see, this table uses percentile dice to determine the chance of a party getting lost in the wilderness, by terrain type:

These d% ranges very closely approximate the "x in 6" chances listed on the analagous "Getting Lost" table in Cook's Expert rulebook on p. X56:

That is,

15% = 0.9 in 6 = approx. 1 in 6 (Plains)
32% = 1.92 in 6 = approx. 2 in 6 (Mountains, Hills, Woods, Ocean)
and obviously, 50% = 3 in 6 (Swamp, Jungle, Desert)

This discovery made me curious, and so I consulted a couple other sources: OD&D's The Underworld & Wilderness Adventures and Gygax's Dungeon Master's Guide. [The Swords and Wizardry Core Rules are excluded from my sample because they have no "Getting Lost" rules at all.] Guess what? With one exception (that wacky DMG), these rules sets (Cook included) all deploy the same d6-based mechanic for getting lost.

The "Lost Parties" Table from The Underworld & Wilderness Adventures p. 18.

And while Raggi's Lotfp WFRP rules employ a slightly different mechanic, based upon the "Bushcraft" skill of the PCs (see Grindhouse Edition Rules and Magic p. 34), that skill system of his nevertheless uses the same "x in 6" mechanic that seems to be the prevailing choice for D&D authors.

As I just noted, the AD&D DMG is a notable outlier, for it uses an "x in 10" mechanic for lost parties -- here is the relevant part of its "Becoming Lost" Table from p. 49:

Obviously, this table disrupts the consistency of my sample, but hey, it is AD&D after all.

So, DMG aside, Proctor's Labyrinth Lord is the only classic D&D iteration I've looked at that uses a d% system for Getting Lost, and may also be the only one using percentile dice for dungeon stocking (I know Moldvay/Cook use d6's). I'm not complaining here -- for while I do generally prefer "x in 6" systems for in-game use, I have actually been enjoying using LL's d%-based dungeon stocking tables lately -- but I do wonder what made Dan Proctor go this route when basically no one else does?

Perhaps I should truck on over to the Goblinoid Games Forums and ask about this directly. But I wanted to get my thoughts out in a coherent way here first, and to see if anybody else in the blogosphere can shed light on this matter for me.

Any thoughts?


  1. I hadn't noticed the preponderance of d%, but I had noticed that the dungeon stocking table is d% while it was d6 in Moldvay. It is set up a bit differently, too. On the percentage, "Unique" rooms are 25% likely (76-100), while on Moldvay's Basic they are only 16% likely (6 on a d6, I believe). That's not huge, but it is significant.

  2. The original games didn't use %'s so as such reproducing a table expressed elsewhere in dice ranges as %'s wouldn't be a copyright violation in any manner.

  3. @Alexey: Thanks for the math there -- I have actually noticed a somewhat high frequency occurrence of "Unique" in my random stocking. I don't mind this terribly, but that slight difference explains it.

    @JD: It sounds like copyright issues are the main reason then. Thanks for the explanation.

  4. Carter I continue to find THE TOWER OF DEATH to be like the coolest name for an adventure ever! (Especially when written ALL CAPS.)

    Any plans to publish the module once you're done with it? I've still got my con game "Beneath the Radiant Dome" on the back burner for PDFing...

  5. @Gavin: Thanks! I suppose I could publish it after the con -- let me see how it runs first!

  6. Avoiding duplicating the original for legal reasons are probably the best guess to why this is the way it is.

    But, it also harken back to when Dave Arneson was mixing d6 and d100 in his game, and converting the classic d6 his wargamer buddies knew to his newfangled d100 mechanic.

    Proper old school! :)