Refactoring OD&D's Wilderness Tables

18 Nov, 2024

The OD&D wilderness random encounter tables look like this:

They imply a very wacky setting.

I've been re-arranging and re-writing some OD&D material for personal use and wanted to see what these would look like if I compiled all possible results into one big table for each terrain type. A few joins & pivots later, I ended up with this:

• As written, the 'Optional Swamps' table is superfluous because there's no chance to roll 'Anmls.' in the first table. I opted to swap it in for the second Undead entry -- the ghouls and zombies have plenty of room to shine on the dungeon table, and I want dinos dammit!. Similarly, I opted to use the Martian entries for the desert table (not sorry).
• I replaced the specific dragon color entries with a generic 'Dragon' since their entry in Monsters & Treasure specifies a preferred terrain type for each color and it doesn't change their collective prevalence.
• Excepting desert and city, the original tables ought to function as d6xd12 tables, yielding 96 possible results. However, some tables only having 8 entries makes evenly refactoring to d8xd12 difficult -- they have a 1.5/96 chance of coming up. The tables above round everybody to a d% range instead (for those not going all the way to 100, the missing numbers could be 'dealer's choice' or 'silly recurring NPC').

These are much closer to AD&D-style 'kitchen-sink' encounter tables than I was expecting. Flying-types are well-represented, especially dragons (thanks to appearing on both the 'Dragons' table and the 'Flyers' table). Lycanthropes are also surprisingly abundant -- full moons in the OD&D settings must be terrifying. Conversely, I was surprised by how rare encounters with Orcs, goblins, kobolds, etc. are. Most of the humanoid encounters are with the various bandit subtypes.

Lairs

I was curious how these encounter frequencies interact with the %lair stat. The rules around lairs in OD&D remain unclear to me, but if treat %lair as the chance that a random encounter represents a lair present in the hex, we can multiply the random encounter odds by the %lair value to get relative lair abundance for different terrain types.

So I threw together another csv file, doing my best to fill in the blanks where %lair information is missing. I used the values in this fan-made OD&D Barsoom sourcebook for the Martian types. To fill in some of the other entries, I drew on Delving Deeper. Animals were given a %lair of 0 unless the concept of a lair seemed relevant to domain-level gameplay (e.g. giant ants).

I also tallied up hexes by terrain type on the Outdoor Survival board:

We can calculate the number of lairs generated by traveling through every Outdoor Survival hex as: Expected encounters * Odds of rolling a monster * %lair = Expected # of lairs. Rounding to the nearest whole number results in the following:

Dungeons & Dragons indeed! Flying types are probably over-represented; perhaps their %lair chances should be broadly lowered since they can range so much farther than other monsters. But what really stands out is that the chances of rolling a lair are actually pretty low overall. I'd be curious to hear if that resonates with people who have run long OD&D campaigns & used the wilderness rules.

Of course, these numbers are what we'd expect visiting every hex a single time, which isn't a realistic way of experiencing the Outdoor Survival map.

I'm still drawn to the idea of placing lairs in advance -- as well as rolling up castles ahead of time. If the number of expected encounters is doubled, we get this:

This seems like a more satisfying spread, though placing 197 lairs seems like a lot of work.

#game-design #odnd #random-tables