5e - Alternatives to Darkvision

Darkvision is fairly common among the character races in D&D 5e.

Dwarves have it, elves have it, gnomes have it, half-elves and half-orcs have it, and so do tieflings. Only humans, halflings, and dragonborn don't, at least among the races in the Player's Handbook.

Open up Volo's Guide to Monsters, and you'll find darkvision among aasimar and tabaxi, among all the monstrous races available for player characters - bugbears, goblins, hobgoblins, kobolds, orcs, and yuan-ti - along with a few more who don't, like goliaths and tritons.

Because almost every species has darkvision, it doesn't end up having much effect in play. Being able to see in the dark doesn't make you feel special, and can't become a key facet of your character's personality, if everyone else can do the same. Likewise, darvision never offers a character the chance to reveal hidden information none of their party members can discover if everyone knows that information by default.

So it would be more interesting, I think, from the standpoint of both characterization and information gathering, if different characters had a variety of different abilities, instead of all having the same one. It makes sense that Underdark natives - drow, duergar, svirfneblin - might have true darkvision, but this ability will feel more special if they're the only ones. I would also for sure let them see right through magical darkness.

I've made a list of some possible replacements. I've assigned them based on species, but you could also roll the dice, or just pick one you like. After the list, I have some thoughts about what it means for 5e to be designed so that so many player characters end up with darkvision. You could also add any of these abilities to a magic lantern or to a pair of glasses, like Luna Lovegood's spectra-specs. You can't really do that with darkvision, since every lantern already grants the ability to see in the dark. (Although I do deeply love The Manse's idea - orcs can see in the dark because their eyes glow red, and you can make a lantern by filling a glass jar with orc eyes.)

If you add to the list, make sure not to include things like "knows true north" or "can accurately guess distances" or "can count all the coins in a hoard on sight". Those might be superpowers in real life, but most GMs regularly assume that all player characters can do all of those things; it's ingrained in the way we share information with players. Offering those as special abilities is either going to be a cheat to those players when everyone else gets the same information anyway, or its going to impoverish your game by removing several common ways of communicating about the game world.

The senses listed below could be "always on" or they could require concentration to use. Some of these senses more-or-less replicate the effect of a spell. If that bothers you, you could make it take as long as a ritual to use effectively. You could also rule that some of these senses only work in total darkness, giving the players and incentive to douse the lights. If you don't like any of these options, you could also remove darkvision and replace it with a language, or with another proficiency.
 

image from Spelunky

ALTERNATIVES TO DARKVISION

Hill Dwarves - Gold Sense
Some hill dwarves possess a "gold scent" - they can literally smell the presence of gold, and the greater the concentration, the stronger the smell. They can tell when they're in the immediate presence of gold, and are drawn to the largest supply in the area - unless that's already on their person! (This one is adapted from DCC.)

Others possess a "gold sight" that lets them see gold glowing with a warm yellow light. A single gold coin gives off less light than a candle, but a small cache will shine like a torch, and a hoard like the noonday sun.

Mountain Dwarves - Trap Sense
Raised in labyrinthine halls amidst every available architectural trick and travail, mountain dwarves have an innate sense for building features intended to deceive or deal harm. In any built environment, they'll notice when they're in the presence of a "trick" or "trap" although they won't automatically be able to identify the nature of the hazard.
(Yes, "find traps" is a 2nd level spell. So is "darkvision".)

Duergar - See Invisible
The diabolical duergar have mastered the magical art of turning invisible at will. With proprietary alchemical paints, they've also filled their cities and lairs with invisible hazards to ensnare invaders. What is invisible to outside eyes is not simply visible to the duergar, it actually glows with ghostly white light to their eyes.
(This could be in addition to their darkvision, instead of replacing it.)

High Elf - Aura Sight
Millennia of schooling and study have trained high elves to recognize magic on sight. Every living spellcaster possesses a faint aura, as does every magic item, and every creature with a magical attack. Depending on the circumstances and the strength of the magic, these auras may be faint, sometimes almost invisible. Powerful auras glow like a bonfire of magical potency.

Wood Elf - Door Sight
In ages past, every forest was filled with hidden doorways that led directly to the Feywild. Today, nearly all of those doors are gone, but wood elves retain a special sense for noticing the presence of secret passages. Doors that are hidden or locked by magic appear as glowing rectangles. Other doors might not be visible, although the elves will know they're there. The means to open these doors will not usually be obvious.

Drow - Poison Scent
Surrounded by scorpions and spiders, successive generations of their leaders assassinated by tainted food, adulterated drink, and poisoned blades, the drow have evolved an infallible nose for toxins of all kinds. They know when rations are unsafe, when monsters are venomous, and when weapons have been coated with poison. Drow with particularly discriminating palates can even identify different types of poison by scent alone, although such sommeliers require additional training in alchemy or herbalism.
(This is in addition to darkvision, however, drow just get regular old darkvision, not the superior kind.)

Stout Halfling - Food Sense
These hereditary gourmets have a knack for finding edible morsels. When foraging or examining the corpse of a monster, they're able to the safest and tastiest portions. Except in unusual situations, poisonous  items that offer no nourishment will appear obviously inedible. Stout halflings can also "follow their noses" to locate kitchens, larders, pantries, feast-halls, and even occasionally guardposts where meals are taken or prepared.
(This replaces Halfling Nimbleness, which becomes a Lightfoot ability only.)

Forest Gnome - Hazard Sense
The untamed wilderness is full of natural perils, and territories controlled by other species are more dangerous still, littered with abandoned siege weapons, crumbling border fortifications, and half-forgotten anti-invasion ordinance. Forest gnomes, who claim no territory and wander freely across the frontier and the settled lands, have encountered all of them. From infancy they learn the tell-tale signs of danger, and as long as they're outside, they know when a trap or natural hazard is present, although its source might not be readily apparent.

Rock Gnome - Machine Canny
Even rock gnomes who don't build machines themselves understand how they work, an ability that appears near-miraculous to other species. To gnomish eyes, every machine is made of parts that operate by cause and effect. "Cause" one part to activate, and its "effect" becomes the cause for the next part, and so on until the machine completes its final effect. While they have no special talent for spotting mechanisms, a rock gnome who notices a machine part can intuit its "cause" and its "effect" and can guess what kind of part comes before it and after it. They can also tell if the part is broken, or if its link in the chain of cause and effect is broken.

Deep Gnome - Gem Sight
Although everyone perceives gemstones as lustrous, to deep gnome eyes they literally glow, the color of the light determine by the color of the gem. Raw and uncut stones give off a dim light that aids in mining, while finished jewels cast a brilliant sparkle. Though unlit to outside eyes, deep gnome cities and lairs appear filled with rainbows and kaleidoscopes to their builders, with strategically placed gems drenching every corner in colorful light.
(This could replace darkvision, leaving svirfneblin on equal footing with others outside their own territory.)

Half Elf - Fey Sense
The elfin blood in half-elves veins calls out to other fey, granting them a powerful intuition that is felt more than seen. Half elves can identify fey creatures, and can tell the difference between those native to the Feywild and those born into the material world. They can identify radiant magic and positive energy. They can identify fairy pranks, even before the prankster has been spotted. They can see the bond between warlocks and the Archfey and the Celestial; and they can tell when someone has been charmed, frightened, or possessed by a fairy or celestial.

Half Orc - Shadow Sight
Born between worlds, half-orcs can see just past the veil between worlds, into the Border Ethereal and the Shadowfell. They can perceive ghosts and fiends lurking invisible and incorporeal, whenever they are close enough to manifest. They can see the difference between dead bodies and the undead, between ordinary shadows and shadow-monsters. Half orcs can see the bond that connects warlocks to the Raven Queen or the Fiend; can perceive when someone has been charmed, frightened, or possessed by an undead creature or fiend; and can see necrotic magic and negative energy whenever they're used.

Tiefling - Mind Reading
If a tiefling can look directly at another being and concentrate, they can actually hear the other's thoughts, the voice in their head like a half-whispered, half-mumbled monologue. This only works if the tiefling can see the others' eyes, the windows to their soul. They hear surface thoughts only, and can't elicit or insert specific ideas, but their infernal ears are especially attuned to thoughts of temptation and desire.
(Like "darkvision" and "find traps", "detect thoughts" is also a 2nd level spell.)

Other Options
When designing a new 5e race that you're tempted to give darkvision, ask yourself if any other divination ability might be more thematically appropriate. Does your species have infravision, able to see heat signatures, but unable to detect oozes, constructs, undead, or even lizards, fish, or amphibians against the ambient air temperature? Can they dowse for water? Are they magnetically drawn to the presence of iron? Can they see emotions? Can they hear lies? Are they able to perceive cosmic alignment, or see the umbilical threads that bonds believers to their deities? Can they sometimes talk to insects or plants or rocks? Can they speak with the recently dead? Be creative, and your world, and your players' experiences, will be richer for it.

image from Legend of Zelda: A Link to the Past

WHY I THINK DARKVISION NEEDS ALTERNATIVES

So, maybe almost every species has darkvision. So what? Is that a problem? Well, maybe. I can think of two possible reasons for 5e to be designed this way, although of course I'm only speculating. The first possibility is that darkvision isn't really intended to be relevant in play very often or to have a frequent mechanical effect. Maybe it's mostly meant to be a nifty factoid about your character, something flavorful to distinguish the various demihumans from humanity, but ultimately no more important than green skin or pointed ears. (Although if so, it ultimately makes humans seem like the strange ones, cursed with a night-blindness that doesn't afflict anyone else. And at least "I have green skin" and "I have pointy ears" mark actual differences between half-orcs and half-elves!)

The second possibility is that WOTC is scared to death of resource management play, and doing everything in their power to prevent it. Maybe they think that only asshole GMs run resource management games, and want those assholes to stay away from their popular new edition. Maybe they're afraid that a novice GM will find an asshole OSR blog exhorting that "Gary wants you to count torches", will naively try to run a resource management game, and will end up driving themselves and their novice player friends right on back out of the hobby after a single bad session.

Whatever the reason, one thing is clear. Between the ubiquity of darkvision and making the "light" spell a cantrip with unlimited re-use, it's basically impossible to run a game where the player characters get trapped somewhere because they're unable to see.

Now, I've been very vocal in the past about not wanting to run a darkcrawl game, but I also don't really care for solutions like this. They feel dishonest. If you don't want to play a game where it's possible to get trapped in the dark, then don't, but don't pretend to offer it as a possibility with one hand, while using the other hand to smuggle it back off the table. Don't make a rule, then give every player permission to break it. Don't claim darkness is important, then fail to write any procedures that would actually support using it, then try to escape the contradiction you've set up by handing out "get out of dark free" cards.

Be honest. Tell potential GMs "The rules of this game assume that a low level of lighting is available at all time. Whether from moon and starlight outside, phosphorescent fungus growing in caverns and tombs, intelligent monsters lighting candles and braziers to illuminate dungeons for their own purposes, or from the player characters bearing torches and lanterns - it will never be truly dark. If your fictional solution involves the characters wielding light sources, these should never cost treasure to supply, never run out, and never count against the characters' encumbrance limits. Assume they are omnipresent, like the clothes on the characters' backs. This is not a game about counting torches or mapping caves in the dark." Then set the example and teach novice GMs how to do this by using the read-alouds and box-text in your sample adventures.

That would have pretty much the same effect as the current arrangement, but it would have the benefit of not pretending to do something you really don't, and it would allow GMs and players who want to engage in resource management play to do so without having to rewrite the spell list and nearly every species' racial traits. Ironically, under such an arrangement, the rules themselves would be more agnostic toward RM play than they are now, when they claim to take no official stand, but then saturate the game world with so much darkvision and magical light that RM play is rendered impossible in practice.