Monday, March 25, 2019

Infravision Instances

I've spent a silly amount of time recently thinking about infravision. In particular: Should it be nullified when nearby to a torch or lantern? And what is the point of that rule in the first place?

See, in OD&D by the book there is no such rule for infravision being spoiled near artificial light. It seems like a rule that Gygax came to between the OD&D and AD&D publications. It is on AD&D DMG p. 59. It was missing from the Holmes Basic draft manuscript, but was added for publication, presumably by Gygax (p. 10; see Zenopus Archives). We're told by Ernie Gygax that what Gary had in mind was specifically this scene from the original Westworld (1973).

But it makes so little difference in-game that I've been ignoring that rule for a long time now. The DMG says, "It requires not less than two segments to accustom the eyes to infravision after use of normal vision" -- two segments being a small fraction of a round, so I'm not sure how that would ever make a difference in play. I suppose there's the range issue: infravision is 60', and torches as of AD&D light a 30' radius, so I suppose that cuts down the distance. But on the other hand, OD&D says that monsters are seen at 20-80' (Vol-3, p. 9), and AD&D likewise says "A light source limits the encounter distance to twice the normal vision radius of the source" (DMG, p. 62) (as well as real-life experiments supporting the same thing, here; login required) -- so it seems like effective visibility is back to at least 60', equal to PC infravision. Moreover: I'm pretty sure none of us play like the monsters are blinded by PCs with a torch as in that Westworld clip, right?

So in these cases my approach is usually to research what would happen in real life as always the most solid, stable, and consistent way to play it. Previously I've used thermal-vision goggles as a serviceable model. Looking for real-world biological organisms with infravision is somewhat more elusive. Interestingly, there seems to be a lot of active progress in this area in recent years among biology researchers:
  • Snakes have specialized heat-sensing pits on their heads (2010).
  • Mantis shrimp can see deep into ultraviolet and deep red wavelengths (2014).
  • Zebrafish and bullfrogs produce special chemicals that can situationally shift their vision to near-infrared (2015).
Then, most incredibly on the day that I wrote this post, a new piece of research broke: Researchers in China and at U. Mass injected nanoparticles into the eyes of mice, altering them to perceive near-infrared light -- and this might soon work for humans. Pretty amazing! The claim also is that this treatment leaves the standard visible-light perception unchanged.

For all this, the burning question remains; if an infrared-sensitive creature stands near a hot torch or lantern, is its infrared visual capacity ruined? This does not seem to be a thing that anyone has tested to date. In fact, a few weeks ago I emailed one of the leading researchers in this area and asked, "If there is prey nearby and another very hot artificial source (say, fire), does the animal fail to detect the prey?". He kindly took the time to reply with: "Daniel, I don't know the answer to your question" (and also sent the inquiry to a second researcher). So: Still unknown as far as we can tell from current state-of-the-art science.

But I still can't quite see what the point of that rule was in the first place, actually. Perhaps it's just a totally academic issue.


Saturday, March 23, 2019

Stats Saturday: Hydras

Generally we've found in our analyses of Equivalent Hit Dice (EHD) power-ratings for OD&D monsters that the danger level is linear in hit dice (for example, see here or other "Monster Metrics" posts). We've taken this to  support a linear system of XP awards per Hit Die (e.g., the original Vol-1 system of 100 XP/HD over the later graduated table from Sup-I and all later editions).

Here's one notable exception: Hydras. As you can see in the chart below, Hydras are distinctly quadratic (parabolic) in their relation between HD and EHD. This isn't too surprising, because unlike other monsters Hydras are getting a double increase in attack potential per hit die (head): both adding to numbers of attacks, as well as increased chance to hit per attack (as by HD). In other words, they escape from the standard "action economy" limitation of most boss monsters, and wind up confronting PCs with staggering numbers of high-potential attacks per round.



Alternatively, one could approximate Hydra EHD in the allowed ranged with a linear regression of EHD = 2.26 Heads − 4.73 (R² = 0.99), or whatever level to which you want to round that off.


Tomorrow on the Wandering DMs Livecast:  We plan to discuss issues around adjusting your game for Conventions versus Campaign play. Tune in Sunday at 1 PM EDT (UTC -4) and add your comments and questions to the chat!

Monday, March 18, 2019

More from Three Hearts and Three Lions

I recently re-read Poul Anderson's Three Hearts and Three Lions. This is, of course, a critical piece of literature for D&D scholars (and other Appendix-N readers), granted how many ideas that were baked into the DNA of D&D originated here. Most of us are aware of the big-ticket items: Alignment (the cosmic system of Law-vs-Chaos; prior looks one, two), the paladin with a holy sword, a Scottish-speaking dwarf, and the swanmay (see also: mythological swan maidens).

However, with this read-through I was paying more attention to lesser-known, possibly overlooked tidbits, that either are or could be used as core parts of our game. My notes follow (page numbers from 1993 Baen printing):
  • General emphasis on smells in sense-descriptions.
  • Ch. 5, p. 46: Land permanently in twilight for Chaos types (e.g., goblins).
  • Ch. 6-9: Lots of interesting faerie magic, customs here.
  • Ch. 7, p. 55: "All of them [elves] seemed to be warriors and sorcerers"; menial work done by goblin/kobold slaves. (Meanwhile, elves cannot bear the presence of a cross or hearing holy words; see Ch. 3, p. 33; and Ch. 9. p. 76.)
  • Ch. 7: p. 57: Castle with magical moat, always circulating. Lord’s host sallies forth from castle (compare to Vol-3 castle behavior?). 
  • Ch. 8, p. 70: Doorknob turns to speaking mouth (magic mouth?) in castle of Faerie Duke, among many other enchantments.
  • Ch. 10, p. 85: Supernatural enemies harmed by ultraviolet light. 
  • Ch. 12, p. 102: Law/chaos used interchangeably with good/evil (last line of big paragraph). 
  • Ch. 12, p. 107: Giants always carrying gold (and p. 113). Giants (“Great Folk”) sit in wintry halls for centuries practicing contests of skill, especially riddles. 
  • Ch. 12, p. 114: Giant (et. al.) turned to radioactive stone by sunlight.
  • Ch. 13, p. 118: Iron passes through werewolf’s body without doing harm. 
  • Ch. 13, p. 119: Lycanthropy is generally inherited. May be bear, boar, wolf, “or whate’er the animal may be for the person”. Lycanthrope “Wounds knit upon instant” (from non-silver). Possible recessive-trait werewolf who turns only when chaos magic ebbs over the land.
  • Ch. 14, p. 132: Iron hurts lycanthrope in human form.
  • Ch. 15, p. 142: Description of enchanted Avalon, magical island drifting over sea.
  • Ch. 15: p. 144: “Ever-filled purse” advertised on magician’s sign (as Bucknard’s everfull purse). See also Ch. 17, p. 162. 
  • Ch. 15, p. 145: Magician with diploma from magic university.
  • Ch. 15, p. 146: Invisible (unseen) servant.
  • Ch. 17, p. 160: Geas prevents spirits from assisting with divination.
  • Ch. 19, p. 176: Nixie who tries to capture the protagonist. 
  • Ch. 19, p. 180: Undersea weed-house.
  • Ch. 22, p. 217: Troll fights with dismembered hand, leg, jaw, ropy guts (!).
  • Ch. 24, p. 230: Presence of Hell Horse (note 1941-1944 art journal in occupied Denmark called The Hell-Horse [Helhesten]). 

Edit: Mike Mornard helpfully confirmed on the OD&D Discussion board that the Vol-3 castle behaviors, as established by Gygax, were in fact inspired by the action in Three Hearts and Three Lions (as well as various Arthurian tales). See here.


Monday, March 11, 2019

Magic Distribution in OD&D Dungeons

An observation: Boy, magic is really rare if using the dungeon treasure table in OD&D Vol-3 ("The Underworld & Wilderness Adventures", i.e., the DM's book). Prior to this table you get the dictate, "It is a good idea to thoughtfully place several of the most important treasures... Naturally, the more important treasures will consist of various magical items and large amounts of wealth in the form of gems and jewelry." Then for the rest of the dungeon, rules that 2 in 6 of rooms have monsters; with treasure present 3-in-6 with monsters and 1-in-6 without. Then this table is given for such treasure:


Now, I've sort of made my peace with this table for gems & jewelry; while rare (esp. at the lower-numbered levels), when present they come in batches and generally large values, so they sort of give some reasonably high value. (A bit like hockey or soccer: scoring is rare but each goal makes a big difference!) However, magic is very rare throughout dungeon levels 1-3, apparently only shows up one item at a time, and has the added limitation that when you turn to the magic tables, 25% of the time it turns into a treasure map, and not actually any magic.

Let's compute. Say on a standard piece of graph paper you get around 40 rooms per levels (that's what I tend to get), and randomly stock the whole dungeon with this method. Then on the first 3 levels combined you'd expect (adding terms for both with-and-without monster cases): 3 levels × 40 rooms × (2/6 with monsters × 3/6 treasure + 4/6 without monsters × 1/6 treasure) × 5% = 120 × (1/6 + 1/9) × 5% = 120 × 0.277 × 0.05 = 1.66 positive results for magic items. Adjusting for the chance of maps, we get 1.66 × 0.75 = 1.25 actual magic items. So on average we may likely get just one single potion on all of levels 1-3 of the dungeon, and no other magic whatsoever. That could make it a bit hard to fight 4th-level monsters like lycanthropes, gargoyles, or wraiths, that start showing up on the [checks notes]... um, 1st level of the dungeon.

Anyway, here's a complete table of expected number of magic items (discounted for chance of maps) per dungeon level under these assumptions:


As we've seen, on levels 1-3 we only expect about 1/3 of a magic item per level, so rounding to the nearest integer, this appears as zero (0) in the table above. At other levels you may get 1, 2, or 3 magic items on average from the Vol-3 random method. If you make a dungeon of 12 levels (~500 rooms?), then we'd expect a grand total of around 14 magic items in the whole complex.

So I think that most of us would agree that simply can't stand; we have to do something else to supply fighters with magic arms and armor, wizards with wands and spell-scrolls, non-renewable potions of healing et. al., and other stuff. The most obvious way is by DM fiat, thinking of the "thoughtfully place" dictum. But then we are left with no other guidelines for what kind of distribution is recommended in that advance process.

Perhaps one faint idea is to shift magic-positive results from one single item to 1d6 at a time (roughly tripling the numbers estimated above, on average). Any other ideas?


Edit: Some folks in the comments take the interpretation that maps should not be generated from that dungeon-treasure table, actual magic only (maps for wilderness treasure only). There's definitely an intriguing case to be made there, but I'm not sure it's ironclad.

On the other hand, if we do permit maps in dungeon hoards, then perhaps we should account for the magic items to which they can lead you. Random maps have a 30% chance of leading to a "Magic Map" table, and 10% to a "Magic & Treasure Table". Those are both d8-based, and coincidentally, they each have an expected production of 19/8 = 2.375 magic items (individual results go as high as 5 items!). So together any random map expects to lead to 0.40 × 2.375 = 0.95 magic item. We might as well round that to "1", which tells us that we can effectively just ignore the map discount itself (each map leads to an average of one magic anyway). Either way, we're then back to an expectation of 1.66 items in the first three levels of the dungeon (not a big difference).

Or taking Daniel Wakefield's idea, maybe that gives us a clue for what a thoughtfully-placed "big magic cache" might be: 1-5 magic items or something like that. Other ideas are to scale it to the expected number of items PCs might have per level (almost embarrassed I didn't think of that earlier).

Consider: These days I roughly assume that pre-generated PCs might have a 1-in-6 chance for magic per level in each of 3 categories. (So: a 6th-level fighter with +1 sword, shield, and armor seems reasonable.) That implies about 3/6 = 1/2 item per level. If one PC level correlates with one dungeon level, and we have 4 PCs, then it suggests we want 4 × 1/2 = 2 items per level (permanent items?). Compare that if we say that random magic finds include 1d6 items (similar to the 1-5 range in the maps), then that multiplies our earlier per-level expectation and get 0.553 × 3.5 = 1.94 ~ 2 items per level. So those figures seem synchronous.

On the other hand, if you have big 8-person parties then you might consider the need to double that again? Geoffrey McKinney's stats for B2 indicate the per-area magic rate at about 80% × 50% × 46% = 0.184. So one of my 40-room levels would expect 40 × 0.184 = 7.36 items, or almost quadruple the figure in the prior paragraph. Hmmmm. At least that gives us a starting upper/lower bound for what we might choose.


Monday, March 4, 2019

More Missile Modeling

I've written so many letters on the physics and statistics of missiles, archery, and ballistics that it could sink a warship (search the blog, you'll see). So much so, sometimes it's easy to lose the plot at this time. I figured I'd summarize some of our findings to date.

We have two primary sources of data. One is from Longman and Walrond, Archery (1894) -- as reported by Barrow in Dragon #58, "Aiming for realism in archery" (Feb. 1982). He writes (first noted on the blog here):

English archers use a 48-inch-diameter target in tournament competition... A compilation of the twelve highest tournament results during a one-year period shows that the “hit” percentages of England’s finest archers at three ranges were: 92% hits at 60 yards, 81% at 80 yards, and 54% hits at 100 yards distance.  

A second source of data is from more recent UK "clout" long-distance longbow competitions. Results from a competition in 2016 show that at a range of 180 yards, competitors hit a 12-foot radius target 42% of the time, and an 18-inch radius central target only 1% of the time. (Full data and spreadsheets on the blog here.)

Using that as a guideline, we've developed a simple physical simulation to model archery shots, using an idea I first saw in Conway-Jones, "Analysis of Small-Bore Shooting Scores", Journal of the Royal Statistical Society (1972). The idea is fairly simple: model shooting error in both the x- and y-axes directions as two independent normal curves, which we call the "bivariate normal distribution". (First noted on the blog here.)

The simulation of that is written as a Java program and posted to a public code repository at GitHub (here). If we run that program with settings of precision = 6.7 (extremely high skill!), target radius = 2 feet, and long output form (that is: parameters 6.7 2 -L), then we get to-hit results very close to the 1894 Archery figures (compare highlights to quote above):


Likewise, if we run the program with precision = 1.6, target radius = 12 feet (parameters 1.6 12 -L), then we get results very close to the recent UK clout tournaments:


Also, if we set the target radius of this latter experiment to 1.5 feet (that is, 18 inches), then the hit rate at 180 yards becomes 1%, exactly as seen in the real-world data. Comparing these two data sources, we might be led to think that English archery skill has dropped off precipitously between 1894 and 2016 (precision 6.7 in the former and 1.6 in the latter). But based on the short quote regarding the first data source, we might say that it was cherry-picking its data; the best dozen results across all tournaments in England in a year. Contrast that with the second data source which includes all 30 competitors in one single tournament, whether they performed well or not. So the jury is still out on that issue.

That ends the recap. Now for a new thought: What is the best statistical model for these numbers? Clearly it's capped above and below: the chance to hit (or miss) cannot possibly be more than 100%, or less than 0%. Presumably we want a smooth, continuous curve, and one that can theoretically handle any arbitrary distance. Effectively we have just given the definition for a sigmoid curve, that is, an S-shaped curve seen in many probability cumulative distribution functions. The simplest model for this is the logistic function, as applied in logistic regression analysis.

One problem with this observation is that logistic regression of this sort is not built into standard spreadsheet programs (Libre Office, Excel) like many other types are (linear, polynomial, exponential, etc.) So what I've done below is this: Used the model derived from 2016 clout shooters (second experiment above; precision = 1.6, set target radius = 2 feet); increased granularity of the output to increments of 2 yards (for added detail); converted hit chances to miss chances (because the logistic curve expects numbers to be increasing from left-to-right), and used the online Desmos graphing calculator site (here; thanks immensely, guys!) to regress it to a logistic function. We get the best possible fit as follows:


Note that our regression (orange curve) has an R² = 95.87% match with the numbers from our simulated physical model of UK long-distance clout shooters (black dots). One possible downside: the logistic formula shown in the bottom-left is probably too complicated to use in a standard D&D gaming session. However, a second observation occurs to us: in the central part of that curve, at distances from around 20 to 40 yards (that is, ignoring the parts that are close to 0% or 100%; i.e., the part with maximal rate-of-change), the curve is practically a straight line.

Let's find an approximating line for that "critical" part of the curve. Our regression formula generates the points (20, 0.28) and (40, 0.73) -- so, this is the region where hit-or-miss chances vary from about 25% to about 75%. Solving for an equation of a line through those points (using Wolfram Alpha or good ol' college algebra) gives: y = 0.0225x − 0.17. Note the slope m = 0.0225, which means the chance to hit drops by 2.25% per yard on that region. Converting to feet we get 0.0225/3 = 0.0075, so: 0.75% per foot, or 7.5% per 10 feet. Note that this is freakishly close to the 7.6% per 10 feet figure we saw in the Milks spear-throwing experiment a few weeks ago.

In conclusion: It seems like our data and multiple models are telling us that there's a consistent dropoff in hit rates of around 7.5% per 10 feet, in the part of the range where it matters (neither a near-automatic hit or miss). This is why in the last few months in my D&D game I've shaved this number off to 5% and simply said there's a −1 chance to hit per 10 feet, on a d20 attack roll. But how to account for the extended upper and lower parts of the sigmoid S-curve distribution (where the chances are almost, but not quite, 0% or 100%)? Well, the classic rule to auto-miss on natural "1" and auto-hit on "20" (or something close to that: say they count as −10 or +30) does a fair job of recreating the rest of that model.

(P.S. Keep in mind that the exact hit-or-miss numbers shown above assume a single unmoving, undefended, man-size target of radius 2 feet or so. In practice, we need all kinds of extra modifiers to account for aware, defensive men in the field; shooting at a clustered army of bodies; and so forth. But from what we can tell the specific range modifiers increments would be generally consistent regardless of other considerations.)

Thursday, February 28, 2019

TotalCon 2019 Shots

Last weekend I attended TotalCon in Marlborough, MA for the first time and it was pretty nifty! Didn't run anything (this time), but played in lots of different games. I'd broadly guess that this will become a regular thing. Thanks greatly to Paul S. for convincing me to make the trip. Here's a few snapshots of the events -- and check out the Wandering DMs YouTube Channel for live video recaps we did of these and other events at the convention all weekend.

Welcome!

Gracious gentleman after a decisive victory at the OGRE table

And now we're fighting the Ogre in the Caves of Chaos with my (gasp: actual roll at table) 18 Strength fighter!

Mike Curtis' setup for an experimental DCC pulp-Mars game with a nifty screen made from an album cover he picked up cheap on EBay.

20-person Marvel & Transformers game vs...

... combined Galactus & Unicron! Jumping Jehoshaphat!

2019 Car Wars Northeast Regional Championship

Boss Fight for Breakfast, in which I played Flame, an ancient, huge, spell-using, evil-genius red dragon (see Dungeon Magazine #1, "Into the Fire") vs. 9 high-level PCs. I managed to hit them with multiple illusions, hidden spiked pits and portcullis, paralysis magic, 176 hit points of fire damage, etc. Missed it by thaaat much.

Monday, February 25, 2019

Cleric Spells Refined

Another follow-up to the Wandering DMs Clerics discussion -- and another kind sharing of spell spreadsheet analysis from a commenter here.

Of course, I'm semi-infamous for not using clerics in my D&D games, and neither does co-Wandering DM Paul; they don't appear in our OED house rules, and the concise OED Book of Spells and Deck of Spells cover only wizard magic. But maybe you've heard: some other people actually do allow Clerical PCs! I'll let you clean up your spit-taked coffee now.

In a spirit of generosity, commenter William Heilman (often commonly posts as baquies) put together a concise listing of OD&D clerical spells, broadly following the stripped-down style of the OED Book of Spells, and put it in a convenient format. With his permission I've shared it on our site here. Blessings upon you all.

Thursday, February 21, 2019

Wandering DMs at TotalCon

This weekend (Thursday Feb-21 to Sunday Feb-24), the Wandering DMs -- that is, my friend good Paul and myself -- will be attending the TotalCon event in Marlborough, Massachusetts. This is Paul's "home" convention, whereas I've never been to it myself. Looking forward to it, should be a good time.

Along the way, Paul and I are planning to livestream some "confessionals" in-between events to catch our impressions, takeaways, and lessons while they're still fresh. We'll be trying to make broadcast around our regularly-scheduled 1 PM Sunday time as a wrap-up for the whole convention. So remember to check in a few times this weekend and see what we're up to -- and if you're at TotalCon, please drop by and say hi! You might wind up as one of the first guests on Wandering DMs. (Do we do that? I don't know, we may surprise you.)

While waiting for that, look for the "Dan in Peru" video from last weekend: "How to get a D&D Castle for Half Price". See you soon!

Monday, February 18, 2019

Ozymandias' AD&D Spell Compendium

About 2 years ago [link] I presented an index to the AD&D Wizard Spell Compendium. That's in regards to the four-volume set published by TSR 1996-1998, compiled by Mark Middleton, that reputedly collects all the spells ever published for AD&D throughout the 1E and 2E periods. My work built on that of James Rizza, who seems to be the first to present a database listing of the spells. What I did was to de-duplicate all the spells into normal database form (James made a copy for each possible school of wizardry, etc.), clean up descriptions and typos, add rarities specified for generalist wizards, etc. -- which allowed us to look at some descriptive statistics for the overall work.

Now Ozymandias of the Crossing the 'Verse blog has kindly shared with us a version that builds on our last version; he's been diligently working these intervening years to make it. Where mine had 15 columns of information, his now has: 139 columns. He's added multiple specific fields for different details of each spell's damage specifications, area of effect, what appears to be a tag for all of the different 28 schools of effect and 21 special origins given in the book, and multiple sheets worth of analysis, tables, and charts. Wow! You can get it at his public Google drive here, and read his analysis on his blog here. (Also other good stuff there, like a recent reflection on redesigning the polymorph spell.)

A few broad comments:
  • Ozymandias has down some mild massaging of certain descriptions (areas, etc.) for his house-ruled campaign. I understand why he would do that.
  • He notes being a bit frustrated that this work, in a sufficiently precise form, hasn't been available before. I share that, too. (Anecdote: Circa 2000 I was working at a company pitching a prototype for online Magic: The Gathering. We were struggling to make all the long spell names fit legibly on the digital cards. Ultimately we found that the winning company had entirely punted on the issue, and just let names run right off the edge of the cards, which we would never have considered acceptable. Oh, well.) 
  • He points out that, while providing a large part of his initial motivation, a relatively small proportion of spells in the system actually deal direct points of damage (15%). I've made the point before that in Original D&D, damage-dealing spells are a distinct rarity: there are only 4 such spells in the whole work!
  • Likewise, he also notes being a bit weirded out by what a tiny number of spells use the "reversible" mechanic (4%), and in the opposite direction, how almost no spells fail to have a verbal component (3%), etc., and so wonders if those are really useful mechanics to maintain in the game. This is definitely one of the wonderfully freeing things I find about OD&D, in that in the initial core conception, none of these were part of the system, and we can ignore them. (OD&D actually had all of two spells noted in the text with some reversible capacity -- oddly transmute rock to mud and stone to flesh -- and I simply ignore those reversed options in my game for simplicity.)
  • Also interesting: The most commonly used spell damage die is the d4! I guess I've been playing my OD&D game with everything as d6's so long I've forgotten about that. But: Ugh, d4, awkward. 
 Thanks to Ozymandias for the excellent work and analysis, and sharing this all with us!

Monday, February 11, 2019

Book of War: Battle of Emridy Meadows

Fellow grognard gizmomathboy dropped me a line a few weeks ago to share his play session with our Book of War mass-combat ruleset -- and it's a doozy! The climax of his campaign set in Greyhawk, the big beat-down with the Temple of Elemental, the legendary Battle of Emridy Meadows. With Thrommel IV of Furyondy and Jolene of Veluna on one side, versus a giant mob of horrible monsters and evil high priests on the other. Here's a few photos from his custom battlemap and game pieces:




Want more? Check this stuff out:
Thanks immensely to gizmomathboy for sharing that -- a tremendous game set up!


Thursday, February 7, 2019

Wandering DMs: Dan in Peru

I started a new series on the Wandering DMs YouTube channel this week; specifically, yours truly wandering about parts of Peru (some old, some very old) and making various DM rulings on what I find. This week's question: Are doors in by-the-book D&D reasonable, or totally crazy?



Our plan is to have a new one of these up alternate Sunday afternoons (dates when we don't have a livecast conversation), so if you're informed and/or/xor entertained by that, please do subscribe over on YouTube, so I can get in your face like that promptly.

Monday, February 4, 2019

On Throwing Spears

One of the things I've written more commonly about here is the mathematics of ballistics and ranged combat. [Here are two of the most significant ones: link1, link2. Do a search, and you'll find a lot more.]

Then, in my last update to the OED house rules [link], one of the edits I made was to change the penalty for range from a short/medium/long categorization to a flat −1 per 10 feet shot. The model that I was using previously followed the standard D&D three-step range categorization, but altered the modifiers in question, based on UK long-distance clout shooting tournaments and a computer-simulated model (per links above, and simulator software on GitHub). But in practice (based on my regular campaign game this year) that seemed very weird. While the real-world-accurate model seems like it should be quadratic, what I realized was that a linear approximation is "good enough" in the close ranges where it matters. If the penalty at 480 feet turns out to be −48 when it should really be −32, that is, of course, entirely academic and won't make any practical difference in-game.

Example: Recently my PCs were traveling up a mountainous stairway ridge while under fire from a group of goblins. The PCs were crawling on the stairs to minimize their chance of being knocked off, while attempting to return fire. But the PCs could crawl for a few rounds with no change to their shot chances, and then suddenly in a certain round, the threshold to the next category would be reached, and the penalty suddenly collapsed. The players were somewhat nonplussed by this, and I think reasonably so. Hence the new rule which is both brain-dead simple to compute mentally and makes for a smooth, continuous gradation as opponents close with each other.

In summary: As of my most recent house rules edit, based on both real-world research and in-game testing, we have: −1/10 feet distance to ranged shots. Also I specify a 60 feet maximum range to thrown weapons. (Note that splits the difference between the 3" range in Chainmail [30 yards] and the 3" seen in D&D [ostensibly 30 feet].)

Since I posted that, most enticingly, an new academic paper of interest has been published: Milks, Annemieke, David Parker, and Matt Pope. "External ballistics of Pleistocene hand-thrown spears: experimental performance data and implications for human evolution." Scientific Reports 9.1 (2019): 820 [link]. The background starts with some academic debate about the distance at which primitive spear throwing cultures could hunt prey: Many argue only 5-10 meters? Perhaps 15-20 meters? Some reports assert 50 meters?

What the authors do here is put the issue to a field test. First, they made replicas of 300,000 year-old wooden spears, presumably used by Neanderthals, as found at the Schöningen archaeological site (as shown to right). Then they found a half-dozen trained javelin athletes, set up hay-bale targets at various distances in a field, and had them throw a total of 120 shots (e.g., see picture at top). These shots were captured with high-speed cameras from which they could procure data on accuracy, speed, kinetic energy on impact, etc. From this it seems clear that the impacts could kill prey on a hit.

For my purposes, I'm mostly interested in the hit success rate. Here's the chart presented by the authors, followed by my recreation and regression on it. 



Conclusions: For this data, we see that a linear regression on the chance to score a hit is indeed a pretty good model (it accounts for R² = 86% of any variation). Moreover, the chance to hit drops about 0.76% per foot, that is, 7.6% per 10 feet. That's close enough to 5%, i.e., −1 in 20 per 10 feet, for game purposes, I think -- our current OED rule. And the maximum distance at which any hits were scored is 20 meters, that is, basically 60 feet, also the same as the OED rule. That's gratifying. (The author's main conclusion is that the academic consensus for useful hunting range should be revised upward to at least 15-20 meters distance.)

A few side points: Note that the 60 feet maximum to score a hit on bale-sized target is very different from the maximum distance throwable with the spear. The researchers also had the participants take a few throws purely for maximum distance, and these ranged from 20 meters to a bit over 30 meters (i.e., over 90 feet). Compare this to the base D&D system which fails to distinguish between the maximum bowshot and the maximum hittable bowshot, say. Interestingly: The more experienced throwers (in years) could throw longer distances, something we don't model in D&D.

Another point in that vein is that the hit rates are fairly low. In D&D, granted 4th-level fighters, an unarmored AC 9 target, and say +6 for being motionless/helpless as well, with −1 for 15 feet distance, I would expect to make a roll of d20 + 4 + 9 + 6 − 1 = d20 + 18, i.e., 95% chance to hit (compared to 58% at the first distance in the experiment). But the experiment run by the authors hobbles the throwers in at least two ways. One: "The participants in this study [were] trained in throwing but not in aiming for a target", which reflects standard javelin-throwing competitions today. So perhaps we should lower the equated fighter level in this regard. Two: Hay bales flat on the ground make for a very short target: around 1½ feet, only one-quarter the height of a man or horse, say? (As noted in my own long-distance archery field experiment with older equipment, it's easy to get shots laterally on target; the difficulty is getting the long-short distance correct; link.) The researchers here took a few experimental shots at 10 meters with two hay bales stacked on top of each other, and the hit rate immediately jumped from 17% to 33% (i.e., doubled). So perhaps our D&D model should also include a penalty for the short target. I'll leave crunching those numbers as an exercise for the reader (they work out reasonably well).

It's always super neat to see people putting historical speculations to practical tests -- especially this one, based on a 300,000 year-old find. Major thanks to Milks, Parker, and Pope for thinking this one up!

Friday, February 1, 2019

Clerical Commentary

The second-to-previous Wandering DMs livecast on YouTube (with yours truly and Paul S.) was a discussion of the D&D Cleric class and why we both have abandoned it in our standard D&D games (per OED).

In particular, our friend BJ Johnson was inspired to send us a fairly elaborate -- and in places challenging -- commentary riffing on what we said regarding clerics, healing, and the Christian roots of the class in D&D. At our urging he's posted that interesting essay on his own blog and it's started a further discussion over there -- you should go read it at Saturday Night Sandbox.

And for more like that: Do consider subscribing to the channel on YouTube and tuning in alternate Sundays at 1 PM EST so you can inject your thoughts while the talk's happening live!


Monday, January 21, 2019

Wargames at U.S. Naval College

Over at the OD&D Discussion forums, rustic313 shared some excellent photos from a visit, inspecting some of the wealth of information on use of wargames for training and preparing officers, from the 1880's, through WWI and WWII, to the present day. Amazing stuff. Check it out and consider visiting if you're near to RI.


http://odd74.proboards.com/thread/13356/naval-college-museum-wargaming-exhibits

https://usnwc.edu/NWC-Museum

Monday, January 7, 2019

OED NPC Generator

I uploaded a batch of new code updates to the Arena repository on GitHub (see link below).

First and foremost, there's a new application there, NPC Generator, to conveniently create OED-compatible NPCs that are complete and playable at the table. This includes all the basic races and characters classes, multiclassing for elves, simple magic items, OED feats, spells memorized, names, suggested personalities keyed off alignment, etc. Unlike the other applications, these creations use a random heuristic without simulating the NPC's entire adventuring career (which is currently not feasible for thieves & wizards; maybe someday). As usual, it's an old-school program for old-school gaming; local desktop based-only, with a very minimalist command-line interface. (Java compiler required.)

Secondly, I overhauled the Marshal program (which generates complete listing for bands of Men in the wilderness, including fighter leaders that are generated by simulating their entire adventuring career) to have more streamlined and useful output. Previously, it would print very long reams of lower-level officers in detail; really, a lot more than could reasonably useful in-game. Now it prints only the top 4 leaders (think: captain, lieutenant, two sergeants), which (a) seems more obviously useful, (b) fits much more conveniently on a digest page, and (c) better simulates historical listings (e.g., Civil War company-level rosters).

Meanwhile, the Arena and MonsterMetrics applications work the same. In particular, MonsterMetrics has gone through regression testing so as to confirm that monster EHD (Equivalent Hit Dice) recommendations are the same as they were before.

As always, this code is released with the open-source GPL v. 2 license, so feel free to download, copy, share, edit, fork, use as the basis for a web program, etc., etc. Of course, there's always more work that can be done. But this has streamlined a lot of my game prep, so hope it might helps some of yours, too.



(P.S.: OMG these kinds of programs would be so much simpler if it weren't for multiclassing!)

Tuesday, January 1, 2019

OED Update (v. 1.05)

The last time I posted a new version of the OED House Rules was over a year ago (in September, 2017). Since then I've had the distinct pleasure of getting to run a regular campaign with a great group of cunning players here in New York City. Of course, as players "bang" against the rules in real time, some adjustments have been made. In fact: I've gotten pretty liberal about letting the cosmos jitter in supernatural ways between sessions, and thereby try out new rules on a regular basis, sometimes just for a single evening. Nonetheless, it seems like our favored ruleset tends to get more stable over time, so the New Years seemed like a good time to publicly update it.

Below are some of the more interesting (I think) rules edits in this version, 1.05. Of course, there may be other more minor edits to be found if you look really closely; and I'm always updating the endnotes with more comprehensive historical references, justifications, and side-comments for why we've chosen to do things this way.

Player's Rules

  • Highlight that humans get unlimited level advancement.
  • Dwarf/elf detection keyed to stone/wood materials.
  • Allow 3 retries for thief & wizard skills. 
  • Make spears specialty attack from 2nd rank.
  • Make ranged attack modifier −1 per 10 feet.
  • Adding a new class costs 1,000 XP.

Judge's Rules

  • Added guidelines on advertising for hirelings, expected pay, etc.
  • Light rules made a bit more generous based on recent research. 
  • Insanity Cards recommended for sanity mechanic (link). 
  • Rapelling/rope break rule made only in case of sudden jolt.
  • Wandering monster checks increased to every 15 minutes.
  • Critical hits possibly only for those above 1 HD.
  • Poison: Death in 1-6 rounds (so curatives can help).
  • Healing: Simplified to level + Con bonus per week of rest.
  • XP Awards: Explicit note to use EHD from OED monster database.

Get version 1.05 on the OED Games website.

Enjoy, and hope you have a happy New Year!

P.S.: Have you been watching the conversations on the Wandering DMs YouTube Channel? This past weekend Paul and I debated the utility of the Thief class in old-school D&D. We plan to be back Sunday Jan-13 and regular alternate Sundays after that (1 PM EST).