Sunday, 3 October 2021

Reverse Engineered Adventure Game

This is a post was originally made on 27th September and then removed. Revisions have been made since then. To lay my cards on the table: the objective is to create a gam without the standard attribute array..

When I first put PARIAH up on DTRPG I received a comment accusing me of advertising the product falsely and misusing the OSR label. I made sure a full preview was available and asked the commenter to take a look and see if they were willing to revise their opinion. To my surprise... they did! Not only did they take a look, they also revised their opinion!

By their definition, a game is OSR compatible if a character created can be run-through a B/X , 1e or BECMI adventure module with minimum effort. It's not a definition I agree with, but it did get me thinking: what kind of gaming system could you run through a B/X module with minimum effort?

The Challenge

Create a rules-light system for running old school adventure modules that:
  • ...does not require the GM to amend the text of said module in any way (eg. convert stat blocks)
  • not confounded by elements of the adventure text (eg. if the module requests that a PC must save vs. wands, the GM and player know exactly what to do) 
In essence, this is an exercise in making a peg to fit a hole when the hole was made to fit a very particular peg. While I've titled this post Reverse Engineered Adventure Game I cannot escape the fact that I'm already aware of the shape of the intended peg: I'm not going to treat an adventure module as a found object and try to reconstruct D&D from first principles. Besides: B1, B2 and B3 all include a reasonable explanation of the game itself in the introductory sections, and all of the B series modules contain some kind of message about requiring the D&D basic set in order to play. 

Let's also address a few other precedents for this process:
  • Chris McDowall has mentioned (on numerous podcasts, and almost to the point of self-parody) making his own RPG out of a half-complete version of the boardgame Heroquest...
  • Ben Milton made Knave to be a vehicle for running old D&D modules, while streamlining and simplifying the rules (in particular removing classes).
  • Searchers of the Unknown is an  ultra rules light version of D&D based around the old school stat-block. This is very close to what I was originally intending to do with this exercise (see notes on statblocks, below), and I owe awareness of its existence to N.Giac of the OSR discord.

What's in a Module?

Modules B1-9 embody the old school experience. I'm going to have a quick look through my collection of PDFs in order to assess what they actually ask of a GM.


As stated, this is not an attempt to recreate a game from a total tabula rasa: I'm approaching each module knowing (I think) what a module is for (it is a generative text!), so understand the purpose of the maps they include, and whether these maps are player or GM facing (and why that might be important).

The main thing to note is that maps in old school modules use feet, yards and miles (in accordance with UCS, not the so-called "Imperial" system), and this should translate to other aspects of the game where measurement is important (travel times, weapon range, spell area-effect etc.).

Conclusion: retain antiquated system of measurement

Ability Scores

Using ctrl-F I was able to locate instances of the 6 ability scores in modules B1-B4, noting in brackets when a PC's ability score total was directly reference:

Strength14 (7)14 (0)8 (0)9 (1)45 (8)
Intelligence4 (4)4 (0)2 (0)1 (1)11 (5)
Wisdom2 (2)0 (0)0 (0)1 (1)3 (3)
Dexterity4 (4)9 (0)5 (0)3 (1)21 (14)
Constitution6 (6)0 (0)3(0)2 (0)11 (6)
Charisma4 (3)1 (0)1 (0)0 (0)6 (3)

As can be seen, introductory module B1 contains the greatest number of direct references to PC attributes, with overcoming numerous obstacles being dependent on a character's strength score.

Indeed, ignoring B1 we can see that PC charisma and constitution sores are not mention at all (CON scores are referenced only in relation to pregen characters' hit point totals). Wisdom and intelligence scores are only mentioned in B4 if a character gets possessed by a particular ghost (they take on his mental attributes). PC dexterity is only mentioned in explanations of the rules in the various introductions (as a modifier to ranged combat and AC).

Strength is directly referenced in a meaningful way only in module B4, in the encounter with the shadows in the crypt: the shadows drain 1 point of strength with their attack, with characters at 0  strength dying and returning as shadows.

Sidebar: shadows in B/X and BECMI are not undead. Not sure why other than to pull a "gotcha" on a cleric brandishing a holy symbol. 

Conclusion: get rid of all ability scores except strength?

Question: what else does strength then do, other than act as ? To hit and damage bonus were only added with the Greyhawk supplement (and only in the case of fighters, who were also the only class to enjoy a DEX bonus to AC) were ignored in Holmes' Basic edition. Of course, by the time Moldvay's basic edition of D&D was issued ability scores had been given a generic set of bonuses (and each one ended up doing something).

Retaining strength just to deal with the issue of shadows draining strength seems like a waste of space on the character sheet.

If additional stats are required to deal with a particular obstacle (and B1 has a few of those) then a player can simply roll 3d6 on the spot to work out their attribute at that point in time. However, I think only B1 makes this specific request. Most of the time we can use the ol' Arnesonian 2d6 dice method... but I'll chat about my interpretation of that in a moment.   

Saves & Class

Monster descriptions and traps will make occasional references to saves (i.e. save vs. paralysis when attacked by a carrion crawler, save or die when facing a poison dart trap etc.). Additionally, monster stat blocks usually note the equivalent class and level from which they make saves. Usually this is as a fighter, with the level at which they save being equivalent to their hit dice. However, even in module B1 we encounter monsters saving as thieves (bandits) and dwarves (gnomes). 

One piece of accepted wisdom is that tying saves to attribute scores is logical, often accompanied by incredulous bafflement at OD&D's clunky five save mechanic. I happen to like it. Not willing to mount a defence of it here, as a more eloquent case was presented by Necropraxis more than 9 years ago

Instead of six stats you get five saves. The numbers are determined by your class.

The following save matrices/classes exist:

  • Fighter
  • Thief
  • Elf
  • Dwarf
  • Magic User
Clerics are referenced throughout (they're a whole faction in B4). I'm not sure about clerics.


Finally, the major piece of "mechanical" game data in game is the monster stat block. Here's one from In Search of the Unknown:

Here's Palace of the Silver Princess:

I chose the second one to highlight the fact that despite statements to the contrary, I am going to pick and choose the parts I wish to ignore: there's a reference to an attribute in this first encounter block in B3 and I don't think anyone needs to know what "CH 14,15" means given the context the author provides. Also because I think we can agree that games have moved on somewhat since 1981 or whatever, and Jean Wells may well have been writing with a particular audience in mind.

So yeah, I'm intentionally omitting ability scores if that wasn't utterly obvious by this point!

Anyway, the key takeaways are as follows:
  1. Armour Class
  2. Saves
  3. Hit Dice
  4. Hit Points
  5. #No. attacks
  6. Damage
  7. Morale
  8. Alignment
All of these things have to mean something in game.

As mentioned above, the game Searchers of the Unknown is based entirely around the monster stat block. PCs are always fighters. I love this concept, I think it's great but it's not what I'm hoping to achieve with this exercise.

AC: module-wise, low is more difficult for the PC. We can combine this with a roll-high system by adding it to hit rolls. (This is similar to the ultra old-school method more recently rebranded as target 20)

(just wanted to add that I had an idea for "to hit rolls working as a dice pool of D20s: you roll as many D20s as your opponents AC, and roll for damage on each "20", fighters roll an additional D20 per level. Problem is... who has more than 2d20? And who wants to roll 10d20 when you attack a peasant? I suppose you can add  a "taking 10" rule and reduce it to a coin toss...)

SAVES: See para on saves above

Hit Dice/Hit Points: I'd honestly really love to do away with HP and leave it up to HD, but I think we have to honour it while it's there. At 0 HP save vs death: hit it on the nose and pass out cold, fall below and die, roll over and continue to fight until the next strike.

No. attacks: Seekers of the unknown does a cool thing by increasing this for PCs quite early (think it's a post L9 thing in RAW D&D). One thing I did think of was the light/med/heavy weapon split epitomised in Holmes Basic, but again I think I'll talk about that below

Damage: creatures attack AND THEN inflict damage. Same for PCs I guess.

Morale:  2d6 vs. morale is a core mechanic, but treating combatants in accordance with their intelligence and motivation. This recent post goes about halfway to considering this in an intelligent fashion, but I think it throws the baby out with the bathwater to some extent.4

Alignment: I'd like to see this worked more heavily into the system for some reason. I think because it's there and essentially meaningless beyond RP advice? I suppose you have alignment languages, and a few spell effects but what about...
  1. All arcane magic is chaotic, all divine magic is lawful (I think this is LotFP)
  2. Dwarves are an archetypal expression of "lawful" humanity. However, there are chaotic dwarves.
  3. Elves are an archetypal expression of "chaotic" humanity: however, there are lawful elves (maybe they cast divine magic?).
  4. Humans are neutral.
  5. Dungeons are manifestations of reality folding in on itself due to those aforementioned chaotic forces. 
  6. No Country for Old Men


I have more thoughts, but it's late and for some reason I really want to post this again before any of those thoughts are fully formed. Here they are, in bullet points:
  • D20 save and combat rolls, all else is 2d6
  • No stats but possibly can choose a trait (strong, bright, swift, charismatic etc.) to bestow advantage on some 2d6 rolls (3d6 drop lowest) and saves.
  • Traits could be tied to class but only as XP bonus: the natural choice is "strong" fighter, but you could forego the XP bonus to create something more interesting. Likewise "muscle wizard"
  • I like elf fighter-druids and elf-fighter clerics. I also like chaos dwarf magicians with impenetrable helmets and a troupe of minders like ork weirdboyz from 40k.
  • Modified Holmes basic combat damage based on 1d6. Light weapons get two attacks per round, but at half damage (1d6 if both hit). Medium weapons do 1d6 damage on a hit. Heavy (two-handed weapons) do 2d6 damage but useable only every other round.
  • Optional rule: only fighters can inflict 2d6 damage with heavy weapons, otherwise the only advantage for non-fighters is reach attack from 2nd rank w polearm)
  • Parry option!
  • Use of advantage/disadvantage: no more math (see also "d20 combat dice pool", above)


Searchers of the Unknown

OED Games target 20:

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