Hexcrawl compatibility

[Update 1/2/2024: added Knave 2e]

[Update 11/25/2023: added Beyond the Wall and Seven Voyages of Zylarthen]

[Update 6/26/2023: added AD&D 2e]

[Update 4/21/2023: added Shadowdark]

We are often told that the great thing about OSR is that all of the materials are mutually compatible. The idea is that it doesn’t matter if it says D&D, AD&D, OSRIC, Swords & Wizardy, or Old School Essentials on the cover of the module — regardless you can run it with any of the above with minimal conversion. This makes sense as these editions all have similar rules for a) combat and b) dungeon exploration and most modules are mostly about a) combat and b) dungeon exploration. However what about other play styles? The hexcrawl dates back at least to X1 Isle of Dread published in 1981, but it is increasingly popular now with OSR hexcrawls like Hot Springs Island, Hideous Daylight, and Dolmenwood being esteemed for their creativity and design. Likewise hexcrawl theory is an active topic on the OSR blogs (e.g., the October 2022 Glatisant has four links to hexcrawl theory posts). So the question is, can OSR hexcrawls boast the same mutual compatibility as OSR dungeons? If I buy a hexcrawl that says OSE on the cover, can I trust that it will run OK using Swords & Wizardry? If I write a hexcrawl, is the decision of which edition to identify it with as incidental as it would be for a dungeon?

A hexcrawl is about exploration and resource management relevant to wilderness travel. In many editions, you face random encounters as a function of time, and these random encounters can be brutal. This makes travel time a key issue since the slower you travel, the more danger you face and more resources you consume per unit of distance. Moreover, encumbrance also plays a role since if you’re carrying a lot of gear or treasure, this slows you down. And finally, a good hexcrawl should encourage travel through favorable terrain by giving differential penalties in terms of speed and getting lost by terrain types. There are other mechanics that could be relevant to hexcrawls (e.g., resource management magic like goodberry), but the big one is how fast can you travel, through what terrain, and will you get lost. And it turns out these vary a lot between editions, as shown in the following tables. Note that I ordered these by “family” of rules, with all the B/X varieties together, all the AD&D varieties together, etc. “Miles/day” is for an unencumbered human on easy terrain. I include road travel time as a special case given that systems inspired by B/X tend to have a 1.5x rule for roads. I describe terrain and lost rules as “vague” if it’s a blink and you miss it “DM may adjust” in the middle of a paragraph type rule.

Edition	Miles/day cross country	Miles/day road	Terrain modifiers?	Lost rules?
Castles & Crusades	2mph	2mph	vague	no
DCC	24	24	vague	no
5e	24	24	yes	yes
Five Torches Deep	10 + STR mod	10 + STR mod	yes	no
Shadowdark	12	12	yes	yes
AD&D	30	30	yes	yes
AD&D 2e	24	24	yes	yes
OSRIC	24	24	vague	vague
Hyperborea	24	24	yes	yes
ACKS	24	36	yes	yes
Basic Fantasy RPG	24	32	yes	yes
Beyond the Wall	20	20	yes	yes
Labyrinth Lord	24	36	yes	yes
Lamentations of the Flame Princess	16	24	yes	yes
Old School Essentials	24	36	yes	yes
Worlds Without Number	30	60	yes	no
Crypts & Things	12	12	no	no
Seven Voyages of Zylarthen	~ 15	~15	yes	yes
Swords & Wizardry	12	12	vehicles	yes
White Box FMAG	12	12	vague	yes
Knave 2e	18	18	yes	yes

It turns out that a simple question like “how far can you walk in a day under ideal conditions” varies from about 10 miles to 60 miles! The 60 miles figure for Worlds Without Number is an outlier, but B/X-inspired games in general include a generous road modifier, and so games based on B/X tend to have maximum distances per day more suited to a bicyclist than a pedestrian. If the characters are traveling cross-country, it’s not as bad, but even for cross-country travel B/X, AD&D, and d20 style games still tend to let you travel twice as fast as do OD&D style games. One implication of this is that Swords & Wizardry may be similar enough to Worlds Without Number that you can run a dungeon written for one using the other, but for hexcrawl purposes, you’ll need to rescale the map.

Now there’s the question of what rules should you use. The simulationist answer is to use the Lamentations of the Flame Princess rules. In real life, the average human walking speed is 3mph and a healthy adult can walk about 20 miles a day under ideal conditions. This matches pretty well with Lamentations’ rule that you can go a bit more than that on a road and a bit less cross country. Plus Lamentations has sensible, well-presented, and generally easy to use rules for terrain, encumbrance, and getting lost.

The gamist answer might well be different. Dolmenwood is written with OSE‘s canonical B/X assumptions in mind and so however unrealistic it might be to expect that you could walk from Sacramento to within site of San Francisco Bay in a weekend, those are the assumptions that campaign setting was written with and if you make characters go slower than that you’re throwing off game balance elements like “are these locations within one day’s travel of each other.” In addition there’s always a compromise between what would the ancient or medieval world really be like and what do players from modern cultures expect. Just as we give D&D a capitalist economy rather than simulating some type of gift exchange or palace economy, there’s a certain appeal if not logic to playing to the intuitions of people who regularly commute in cars or on trains and so think of ten miles as a quarter hour, not all day or half a day. In addition, having a road multiplier is a great incentive to funnel characters along set routes.

If you’re writing a hexcrawl for publication, my suggestion is to either a) include the hexcrawling rules in the hexcrawl itself or b) give the hex scale in terms relative to the system’s speed. For instance, “the scale of 6 miles per hex is based on the expectation that, given favorable terrain and light encumbrance, characters can travel up to 24 miles or 4 hexes a day. If you are using a game like Swords & Wizardry with a slower movement rate, you might want to use a scale of 3 miles per hex.” There’s also the radical option of not writing a hexcrawl at all but instead writing a pathcrawl, which effectively replaces the system rules with ones specific to the locations.

Some additional notes.

Several games allow a forced march for more distance. Swords & Wizardry and Crypts & Things both let you “force march” to double your distance by a strength check. White Box FMAG (which shares a genealogy with these games) allows a force march but doesn’t give any downsides to doing so.

Some games, e.g., Swords and Wizardry, gives terrain modifiers for vehicle speed but not pedestrians.

Filling out the table and searching through all the, often poorly organized, rules made me appreciate modern design and organization exemplified by OSE all the more.

Beyond the Wall and Through Sunken Lands (which are mechanically the same game) don’t have hexcrawl rules at all in the core books, but in the supplement Further Afield. There are no rules on getting lost in the travel section but most terrain types include getting lost in the encounter table (which is really more of an encounter and events table).

[Update] Shadowdark (which gets its core mechanics from 5e) has S&W style hexcrawl rules with a base rate of 12 miles/day but the option for a forced march. Unlike S&W and Crypts & Things, Shadowdark uses a CON check (rather than a STR check) and the forced march adds 6 miles per check.

[Update] Seven Voyages of Zylarthen doesn’t have a set movement rate at all but instead the characters roll to see if they move one 30 mile hex. The roll is modified by movement speed and terrain. For instance, moderately encumbered humans in good weather on open terrain have to roll 10 or lower on a d20 to move a 30 miles hex, which makes E(X)=15. In the long-run, travel times in Zylarthen should be similar to Swords & Wizardry, Shadowdark, or Lamentations, but on any given day, travel will be much more swingy than the typical model of “you move a set increment unless you get lost.” I can’t decide if I like this more stochastic mode of travel or not.