I just stumbled across a new blog, Nerd-O-Mancer of Dork, and it seems intriguing so I'm looking through the archives. It's a broadly old-school gaming blog, is probably the simplest shorthand to describe it. One post I found is about some issues with the way darkvision (and its variants) work. Here's the key quote:
Darkvision takes away the suspense of being in a dark creepy location far underground and moreover destroy the suspense for the human players who have to struggle with torches and lanterns.
I do think there's a lot of truth in that. One thing I've noticed is that there's a strong tendency for people to pick non-human characters, particularly amongst my friends with less gaming experience.* A part of demihumans can be mostly unaffected by darkness, which seems like a non-trivial loss. It removes a useful tool for creating atmosphere, adding mysteries, shaping combat encounters, and just plain differentiating one slice of the adventure from another. If there's no apparent difference between being in a dark cavern and an open plain, that seems sad to me.
That's probably because these players aren't that familiar with the rules, and in many cases not that interested in them; they want to make a cool character and have fun adventures, and I absolutely endorse this. Most of the other races are significantly cooler (in various ways) than humans, because we're already all humans, and humans don't get any groovy abilities because, um, we don't have them.** Where humans tend to be particularly good is usually in making particular character concepts, because they're flexible and tend to get extra skills, feats, multiclassing potential or what have you. My experience so far is that newer players are less likely to approach things that way.
** Actually, humans have loads of cool abilities, but we don't notice them much, and then we assume that any vaguely humanoid creature would have all the same abilities we do, plus other ones, because they're just flat-out better. Colour Vision? Resist Lactic Acid? High density of sweat glands to disperse heat? And that's without getting into any cognitive stuff that other races might well be worse at.
Because I like playing with mechanics, I suggested taking Dawnrazor's idea further and devising some rules for how those various *visions actually work. With science, like. Here, I expand on those ideas a bit more than I wanted to as a first comment on someone else's blog.
Decide amongst yourself which kind of *vision a creature actually has. I'd tend to recommend that subterranean dwarves have infravision, for example, while elves might have ultravision for all that starlit dancing.
A guide to demihuman vision
Vision: it's the best! Normal vision in dim-to-bright light is the best model for most of your needs, guaranteed. Sensing shape, colour, movement, fine detail, texture and more, we recommend it for all but the stealthiest of situations.
It’s like vision, only you need less light.
Darkvision is definitionally working without light. You’re seeing some other way. And it’s not a magical ability. It's apparently not sonar, because that's blindsight usually. I’m going to suggest treating this as ‘shape vision’, and assuming it works on some very specific wavelength that's essentially omnipresent. That’s mostly for contrast with the other types below.
Darkvision lets you see shapes and movement, and that’s it. No colour at all for you, and very little detail. You can find the walls of the dungeon and the furniture, but you can’t read this parchment, or even tell whether there's writing on it. It's good for moving around safely, and lets you defend yourself, though you can’t always tell who’s the bandit and who’s your ally without all that facial detail and colour information.
So I'm ruling that it’s actual infrared you’re seeing here, so what this fundamentally gets you is heat. When there’s no normal light to overwhelm it, you can make out sources of heat and cold, but very little else.
This lets you see many creatures quite easily, though not most undead or constructs. You can make out surroundings to a limited extent because different substances react differently to heat – a wooden table and a stone wall will look a little different. Very hot objects seem so bright that it’s difficult to see anything else nearby. A major benefit is you have a chance to see creatures that are lightly hidden, say behind a cloth or leaves. Heat sources leave traces - you may be able to track the heatprints left (very recently) by a creature, and if a room was warm recently it'll still seem light to you.
Suggested by commenter Umbriel on Nerd-O-Mancer of Dork.
This requires a source of ultraviolet light, typically faint starlight or moonlight. The character can see most objects dimly in shades of grey, while many plants and animals (especially insects) have rich ultraviolet patterning. Some mineral substances, including many poisons, are visible to ultraviolet. Some creatures, particularly magical or unnatural entities, may glow with ultraviolet light, making them visible and acting as a dim light source. Undersea or subterranean creatures may have evolved similar capabilities to allow vision, attract mates or find prey.
This was all primarily intended just to make things richer and a bit more interesting. It should also mean that demihumans don't leave humans completely in the dust when it comes to exploring in the dark, which is a large part of most games. Under the standard rules, there are quite strong arguments for never using light sources: if you can see perfectly well with minimal or no light, carrying a lantern primarily serves to attract attention and make you visible to enemies. In many ways a human can just be a hindrance to a party of adventurers who could otherwise run around in the dark.
I’d also tend to rule that it generally takes a few seconds at least for eyes to switch between *visions, in the same way we have to adjust to dark rooms and bright sunny days. So when the lantern goes out, the elf and dwarf aren’t just completely unaffected – they get to spend a round blinking and cursing too.
Using these or similar rules would tend to open up some new kinds of puzzles or confusion for players trying to work out how to interpret colourless shapes or heat signals.
Don't forget, this would apply to enemies too. Players and characters could take advantage of the properties of each monster's vision to distract, confuse or thwart them. New options is generally good.
Of course, it does add complexity, and that's not necessarily what you want. A major advantage of simple darkvision or infravision is that they just let you see in the dark and move on with your life.