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).