Caves of Qud is a post-apocalyptic roguelike game heavily influenced by ADOM and the tabletopGamma World RPG. Set on a future Earth many centuries after an undefined apocalypse, the game takes place in the titular region of Qud, a jungle-like area bordered by a desert of salt and large mountain ranges, and boasting a large number of ancient ruins. This realm is actually a terrible place to live, but still attracts many adventurers due to the abundence of Lost Technology within its borders, particularly within its vast cavern systems. However, things may be taking a turn for the (even) worse, as signs of an ancient evil begin to emerge from the dark and forgotten Caves of Qud...The game is still in active development, and can be downloaded here.
Bears can show up as early as Red Rock, and can be lethal for players who only have a level or two under their belt.
The trope keeps going when you meet the Urshiib (sentient mutant bears), who run the second town most players visit. Not only are they located at the bottom of yet another dungeon, but they insist that you complete a Fetch Quest in a very dangerous location before they'll allow you full access to their enclave.
Blessed with Suck: Most of the mutations have no drawbacks, but a few do, and they can cause you a lot of grief if you're not paying attention. Woe unto the player who too casually uses disintegration (which paralyzes you for a few rounds as part of its "cooldown"), or uses the clone-creating temporal fugue while also having an area-effect attack, or picks the Nomad class (whose biggest perk is a free recycling suit) after taking a mutation that disables body armor...
Bonus Boss: The lairs of legendary beasts can pop up randomly on the world map, and taking them on is optional.
Boring, but Practical: All those copper/silver/gold nuggets you see in merchant inventories? Those aren't just Vendor Trash, they're a much lighter way of carrying your wealth than what they're worth in water. Also qualifying is the basic tinkering recipe for making lead slugs for your guns.
Cool Key: One category of artifact are the colored key cards that can unlock doors of the same color. Unfortunately for looters, keycards of any color tend to be rare and expensive as artifacts go. The Psychometry bypasses the need for these Keycards, as you simply use your biological item scan to help the door "Remember" its passcode.
Crapsack World: Even a thousand years after the apocalypse, most of Qud is still a ruined, barbarism-ridden, monster-infested, and sometimes radioactive Death World with only the most isolated pockets of "civilization". Better yet, you have but to finish the first quest before you receive a big warning that it's about to get even worse...
The Dev Team Thinks of Everything: Perhaps not yet to the level of Nethack, but the game already features such things as being able to douse yourself with your own canteen if you're on fire, or use an enemy's acid spamming to breach a wall.
The Spinnerets mutation allows you to spin webs. If you take the Phasing mutation as well (which allows you to phase out of reality), then activating your spinnerets will produce phase webs instead of normal ones, trapping anyone who is caught in them outside of reality until they escape.
You can use the Kindle mutation to light webs on fire. If you do it with the aforementioned Phase Webs, the fire will be phased out and will only burn other phased-out things.
Dialogue Tree: One feature that helps COQ stand out among roguelikes.
Disaster Scavengers: The player character, by default. The elder of Joppa used to be like this, but now sees himself as too old to risk his life plundering Qud's chrome caverns. (He encourages you to go right ahead, though!)
Disc One Nuke: For players lucky enough to be offered the recipe for a grenade launcher or similarly blasty weapon when they take Tinkering 1 (easily achievable in the first few levels of the game - provided your character is smart enough for tinkering to begin with).
Difficulty Spike: Like many roguelikes before it, COQ isn't at all shy about suddenly introducing some new monster or hazard that can totally annihilate you right when you thought you were safe, or sending you to a new location that will bury you even though you plowed right through the last area without breaking a sweat. The Golgotha sequence particularly stands out here.
Do Not Run with a Gun: Good advice if you've invested in the rifle skills, as passing a turn lets you "aim" and gain a to-hit bonus. More advanced skills along the rifle branch allow you to execute special attacks with your rifle if you're aiming.
Dump Stat: Character creation uses a point system, and - like many such systems - there'll probably end up being at least one attribute that doesn't play a massive role in your particular character build. Mental stats in particular are less useful for anyone who doesn't use Esper powers; Willpower determines your resistance to mental attacks, and Ego is used in the places most games use Charisma (shop prices, recruiting allies), but neither application is particularly essential.
Easy Exp: Looting the homes in Joppa. Did you find any artifacts? You can turn them into Argyle for his first couple of quests and make level 2 before you've even left the village.
Elemental Crafting: Melee weapons and armor can be made of bronze, iron, steel, carbide, folded carbide, crysteel, metametal...
EMP: Some of the weapons and mutations are based around EMP attacks.
Enemy Scan: You actually get some of this functionality for free, as you can see a monster's equipment and how relatively tough they are by simply (l)ooking at them. Having the right gear equipped will let you learn even more about them.
Everything Breaks: You can destroy the walls, furniture, trees, and most everything else in Qud if you have a weapon that can penetrate their toughness. In fact, one of the best uses of the burrowing claws mutation is not combat, but simply to dig around locked doors that you don't have a keycard for. Mutants who overuse the Pyrokinesis mutation in combination with Temporal Fugue (cloning yourself) or high-level Mass Mind (rapidly resetting its cooldown) can take this a step further by discovering that the game's temperature system means that repeated applications of searing fire can eventually burn stone, melting it with such heat that it can rapidly spread and destroy the entire level.
Everything Trying to Kill You: Some of Qud's plant life is just as obnoxious as any of its animals. The qudzu eats your equipment, the young ivory pop out of nowhere to slap you with massive bleeding, the jilted lover plants hold you in place (while eating you, of course), the seed-hurling plants have a better range than your line of sight... and all of those things can be found in the starter regions of Qud.
Fantastic Fighting Style: The sword branch of the skill tree offers several "stances" (with accompanying bonuses) for players to choose from.
Fantastic Light Source: The glowsphere and particularly the floating glowsphere. The latter is especially prized not only because it's expensive, but provides light without taking up one of your hands.
Fetch Quest: Argyle of Joppa is fond of handing these out. Becoming his apprentice involves finding him two separate artifacts, and then 200 feet worth of copper wire.
Flash of Pain: A useful part of the interface is the way your (or a monster's) symbol will briefly change after an attack, letting you know whether the attack hit, failed to penetrate armor, or just missed completely.
Five Races: Averted. The only playable races are True Men and Mutated Humans. (Although plans exist to implement Mutated Animals and Sentient Plants.)
Force Field: One of the more powerful mutations, and practically a must if you've sunk all your points into being a mutation-heavy esper.
Follow the Money: Not money, exactly, but those 200 feet of copper wire that Argyle wants are just laying on the ground of the Rust Wells, and if you're particularly unlucky, you might end up collecting some of it 1 foot at a time.
Hollywood Acid: Played straight with acid grenades, corrosive gas, and other acid-based hazards. The corrosive gas is available as a player mutation and the grenades are craftable, if you get tired of being on the receiving end.
Improvised Weapon: The game will let you attack with any object that you can put in either hand.
Intrepid Merchant: It's possible to encounter random traders while wandering the world map. This is also one of the starting backgrounds available to mutant characters.
In-Universe Game Clock: The game keeps track of (in-game) time. Luckily for players who don't want to be inconvenienced because they stumbled back into town at 2 AM, none of the merchants or quest dispensers ever seem to sleep or close their business.
Item Crafting: An entire branch of the skill tree is dedicated to disassembling the junk and artifacts you find, and reassembling the bits into useful gear.
King Mook: The monster races can spawn uniques and "legendary" variants of their type, both with names and a nice pink color to give you fair warning.
Kleptomaniac Hero: You can get away with looting the houses in towns if no one can see you. This is particularly useful in Joppa at the beginning of the game, since the chests can contain guns, tonics, and other useful artifacts for getting your run started.
Level Grinding: The game makes an effort to avert this (by progressively lowering the XP gain for killing monsters below your level), but grinding in level-appropriate areas is still possible and useful.
Linear Warriors, Quadratic Wizards: Made particularly dramatic by the fact that Ego raises the level of all your mental mutations, but provides no benefit until you're high enough level yourself to use them at that power; additionally, you can spend your chargen points to start with nothing but randomly get a more powerful random mutation later on as you advance in level. This means that a beginning Esper might start with only one usable mutation and nearly all their stat points locked up in a stat that does absolutely nothing at level 1; by level 20 they'll have 12 or so mental mutations at level 10 (as opposed to, say, two level 10 mutations for a physical mutant) and be able to teleport anywhere, clone themselves 7 times, and set the entire area on fire with their mind. And many mutations themselves scale quadratically, like Mass Mind, which refreshes all your other mutations; it starts with a cooldown of 1000 turns and eventually lowers to a cooldown of 5...
Locked Door: A common feature of Qud's ruins. Luckily, the walls around these doors aren't always as Ragnarock-proofed - sometimes the map generation leaves gaps leading to the other side, or you can breach them with powerful weapons, acid attacks, and burrowing claws.
Malevolent Architecture: Fricking Golgotha. Doing your quest there involves jumping down a one-way pit from the surface level, where you land on a conveyor belt that will be quickly overrun by an acid cloud or some other heavily-damaging hazard. The conveyor proceeds for several levels like this, eventually dumping you into a big scrap level that holds the object of your quest - and a horde of monsters eager to finish the job that the Conveyor Belt Of Death started. Afterwords, depending on how you handled the bossfight at the end, you could contract a disease which can make the game Unwinnable for certain builds, particularly characters with regeneration, who can no longer safely eat food, or drink water.
The Maze: The "underground" levels may not officially be a maze, but they apparently reach all over Qud and you can wind up in them if you go too deep in many dungeons.
Mooks Ate My Equipment: The qudzu plants, which can rust your equipment with a hit. Luckily, they can't move. Less luckily, they can spawn on walls - including the walls surrounding one-tile corridors.
More Dakka: Available to those who are lucky enough to scavenge a chaingun.
Nice Job Fixing It, Villain: Those mutant skunks, worker ants, and other monsters that belch clouds of acid at you? You can lure them to that wall or door you can't get past, and let them melt it for you...
Power Incontinence: Some of the selectable bad mutations include teleportitis and randomly releasing EMP bursts.
Practical Currency: Or is that Impractical Currency? The game's basic currency is pure water. This actually adds another layer to the challenge, as water is not only heavy, but you'll also need enough canteens to hold it all.
Random Encounter: The world map throws this trope at you on steroids. You won't encounter random monsters when traveling overland - no, you'll get lost, forcing you to explore one monster-infested zone after another until you finally regain your bearings and are allowed to return to the world map. To be fair, world map random encounters can also be good things, like wandering merchants, ruins with loot, or legendary monster lairs.
Scavenger World: Most technology still can be manufactured with the right knowledge, but most people are seemingly unable to make anything beyond melee weapons and makeshift firearms, with anything more advanced gained through scavenging alone.
Schmuck Bait: The big pink region way over on the eastern side of the world map... the one labeled "Deathlands" and described as "ancient radioactive ruins".
Short Cuts Make Long Delays: A secret tunnel leads from Joppa to Red Rock, providing an alternative to braving the world map... but the monsters in this tunnel are at least as dangerous as the ones around Joppa, and you can get lost in the vast underground map if you take a wrong turn.
Shout-Out: The description for the hologram bracelet is a shout out to Total Recall. You can also build a timecube, which is ridiculously expensive, and doesn't do anything other than give a line from the actual article.
Spike Shooter: One of the uses of the quills mutation. It fires in every direction at once, too, making it great for when you're surrounded by mooks.
Spread Shot: A feature of the shotgun family of weapons.
Squishy Wizard: Dedicated enemy espers are like this. The player can be one by putting all their stat points in Ego and Will and focusing on ultra-long-range mutations, but (due to the point-build system for stats and mutant powers) that's not the only way to make a mental mutant; you can play a psionics-based Magic Knight, Kung-Fu Wizard or a Ninja Pirate Zombie Robot if you prefer.
Status Buff: A few of the mutations specialize in this, and then there's all those injectable tonics...
Video Game Caring Potential: When merchants don't have enough water to complete a proposed trade, you're free to accept what they have anyway.
Trial-and-Error Gameplay: As usual for roguelikes, you'll probably lose a lot of characters learning how to play the game. Luckily, the potential frustration of this is somewhat lessened by all the variety in character creation...
The Wandering You: If you manage to get lost on the Qud's world map (and you will), you'll certainly feel like you're getting brutalized by this trope.
We Buy Anything: Conveniently, any merchant will buy anything you're carrying.
Winged Humanoid: The wings mutation, which can make it a lot easier to deal with hazards (like monsters and getting lost) when you're outdoors.
Wizard Needs Food Badly: Caves of Qud is even harsher than most roguelikes with this trope, as your character needs to eat and drink to survive. And your water doubles as your currency. At one point in the early game questline, you contract a disease which makes both have a chance of killing you.