I recently came across an interesting situation in my solo original Dungeons & Dragons campaign. My adventuring party forced open a door in the underworld beneath the "Castle of the Quest" and subsequently found themselves in a corridor filled with smoke! It therefore seemed appropriate to have some sort of rules to hand regarding vision as surely this vision would be obscured by the smoke and hinder the characters in some way.

Obscured Vision in OD&D

In order to discover which rules might apply (or point me in the right direction in terms of handling the situation) I decided to review all the original D&D rulebooks. In Men & Magic under the spell description for Insect Plague it tells us that this spell "obscures vision" indicating that some such mechanics should apply in the game. In Greyhawk the description of the Horn of Bubbles says it "completely" obscures the holders vision for 4–12 turns. This implies the obscurity has a spectrum from less obscured to completely obscured, so we can keep this in mind. Further, Blackmoor tells us that the Giant Octopi "emit an inky cloud when frightened and/or retreated, which greatly obscures vision." it also tells us in regards to the Helm of Underwater Vision that this helm "allows the wearer to see 180” in any water not blocked by rocks or plants, etc." so there is an implication that vision has a range, which could perhaps be reduced when obscured. Blackmoor states normal underwater vision is 100’, medium seaweed reduces this by 30' as well as movement to 25% and heavy seaweed completely blocks vision beyond 10' and slows movement to 50%. These are great clues.

Before we can begin to look at how vision might be reduced in range it is important to establish what the normal range of vision is. We have already established that under water visible range is 100' but what about the underworld and the wilderness? We can probably extrapolate this by looking at a few other things that are related. Firstly, in the underworld (as per Underworld & Wilderness Adventures) encounter distance is at a maximum of 80' and the book explains that this is the moment the characters "sight" the monsters. This therefore also implies that light sources such as torches and lanterns must illuminate an 80' radius. For the wilderness the distance is up to 240 yards. For ease we can represent all distances in inches so it would be 8" for the underworld, 10" under water or 24" in the wilderness.

We must also take into account light. There are several light spells mentioned in Men & Magic, which offer a radius of illumination at either 3" or 24". The Infravision spell which allows a character to see in total darkness has a range of 4" to 6".

As visibility is dictated by location, light source, and magical abilities that affect site the radius is highly variable, so I think the best way to represent obscured vision in the game would be something like the following (turn your phone to landscape to display the table correctly):

             Range
             Total      Torch     Light   Continual    Full
Location     Darkness*  /Lantern  Spell   Light Spell  Daylight

Underworld   0"         8"        3"      24"          --
Wilderness   0"         8"        3"      24"          24"
Under Water  0"         --        3"      24"          10"

                        Movement
Vision                  Speed      Range

Normal                  Full       Full
Lightly    obscured     3/4        -70%
Heavily    "            1/2        10' max.
Completely "            1/4        Nil

*Dwarves/elves have Infravision so can see up to 6". An Infravision spell has a range of 4"-6".

The above presumes that a Continual Light spell cast underwater would have no restrictions and allow characters to see further, which I think is logical.

Let me know what you think!