"How fortuitous! Evil doom-chicken #3 (second from the left, but otherwise indistinguishable from doom-chickens #1, 2, and 4) had a Great Big Nasty Sword of Serious Hurtfulness + 5. Funny, I didn't notice that sword anywhere on its feathery person while it was still alive. If it was so heavily armed, why didn't it use it in the fight?"
A gameplay mechanic used principally to give a sense of reward to the players by assigning enemies a list of items you might gain if you defeat them. These items are called "drops" because the foe drops them when they die, and there's a probability table assigned to each item the enemy can drop—"Okay, 30% of the time you get a Potion, 5% you get a Red Shield, and 3% you get Cod Liver Oil"—which is where the "random" comes in.
Different kinds of games can do this with different kinds of items, from instant-use health pick-ups to items and equipment that are stored in inventory for the long-haul. Either way, a dry spell of Random Drops can seriously increase the challenge of many a gameplay segment.
If a drop is especially rare, it goes under the subtropeRare Random Drop.
This often results in Impossible Item Drop and Organ Drops. Relative of the Luck-Based Mission. See also Money Spider and Exclusive Enemy Equipment. Also often see with Randomly Generated Loot. When combined with 100% Completion, you could end up with Fake Longevity.
Castlevania: Curse of Darkness has any number of items that only very rarely drop from enemies. This is the only way to acquire many of the materials needed to make weapons and armor. However, most of the materials can be stolen from other enemies, so it's not quite so bad. That being said, since stealing in this game works by locking onto an enemy and then pressing a button when they do a specific action that leaves them open for stealing, some of the items can be even more of a pain in the ass if you can only steal their item with a ridiculously good timing, using obscure gimmicks or avoiding a hard-to-dodge attack with perfect timing and be positioned correctly right afterwards.
Castlevania: Circle of the Moon was particularly egregious in two respects. There is an item that increases the rate of random drops, but this item was also a random drop. There's also a spell that boosts your luck (and thus increasing your odds of getting a random drop), but to get the materials for the spell you needed two random drops (although the odds of getting those drops was much more realistic—no worse than a 10% chance). Remember too, in this game there is no other way to get any items other than through random drops. Even the most basic Potion is a rare drop from just a handful of enemies. The people who made this game hate you and your family.
Castlevania: Dawn of Sorrow takes random drops to new extremes, with most weapons coming from randomly dropped souls... and the soul that increases Luck having 9 levels, so you need to get the soul 9 times. However, this particular iteration is not at all bad, as the creatures that drop the Luck increasing souls are plentiful, easy to kill, and drop the soul quite frequently (it's a two-star drop).
Similarly, in Castlevania: Order of Ecclesia, enemies can drop money, materials used in side quests and Glyphs, OoE's equivalent of Souls. Enemies also cast glyphs, which means that you'll have to absorb them quickly while the enemy is preparing the attack. On the plus side, absorbing the glyph stops the attack, gives you five hearts, and briefly stuns the enemy.
Castlevania: Symphony of the Night has a bunch of really cool (But sometimes impractical) weapons that randomly drop from enemies. Most infamous would be the Crissaegrim that drops at an insanely low rate from one of the game's resident Goddamn Bats. (Though unlike every other goddamned bat these don't spawn nearly as often.) Some locations do allow you to kill enemies with rare drops in rapid succession by switching rooms back and forth quickly if they don't drop the item you want, but that also tends to devolve into a reaction test of actually being able to see the item drop and stop yourself from instinctively changing the room again before picking the said item up, which of course makes it disappear. There's also Heaven Knights, which fly around, are unhindered by walls and appear in an area where they can easily drop their rare item in a location where it's impossible to get even if it didn't disappear in 10 seconds or so.
Castlevania: Aria of Sorrow. Souls. Incredibly common from some enemies (you'll have ten copies of the Bat soul by the time you hit your second boss), incredibly rare from others. The worst? "Tsuchinoko," which spawns in the far corner of one room maybe half the time, and immediately tries to burrow out of sight, and drops his soul maybe one time in fifty kills. There are other bad ones, but he's the worst. Many players have killed it once out of curiosity after killing the boss before its room, gotten the soul, and wondered if that was actually the boss-fight reward.
Sky Fish says Stealth Hi/Bye. Yes, that flicker at the top of the screen in certain rooms is a monster with a soul, and without it you can't get 100% completion.
Every relic except two in Castlevania: Lament of Innocence are found throughout all the levels, like good hidden items should be. With the exception of two. These two are the rare drops for somewhat difficult to kill monsters and it's rather frustrating to try to obtain them...
This goes back all the way to the original Castlevania I and most of the non-MetroidVanias in the series that followed. Enemies would randomly drop hearts, money, or even subweapons, if the game was feeling generous. Which wasn't too often. Maddeningly, sometimes a subweapon you didn't want would be unavoidably dropped, especially when dealing with aerial monsters. Thankfully, most games since Castlevania: Rondo of Blood have allowed you to pick up your old weapon, as long as it didn't fall down a pit.
Castlevania: Harmony of Despair takes this trope and runs away with it. Soma's souls make a return appearance, as do Shanoa's glyphs (though they're easier to get here). However, Shanoa only gets new weapons from chests dropped by bosses, meaning that, unless you want to go through the whole game with her default rapier, you'll be doing some grinding to pick something up. Jonathan also only gets subweapons randomly, which is problematic considering that he doesn't get stronger without using subweapons. Charlotte also suffers, as she only gets spells by using a shield to absorb them from enemies, meaning that you might sit in front of an enemy absorbing fireballs for the full thirty minutes. And then she has to absorb the same spell to get stronger.
Enemies in The Legend of Zelda games usually have pretty consistent drops, but The Legend of Zelda: Skyward Sword introduced "treasure" items, like slime blobs, that drop infrequently from certain monsters. Some, like the Gold Ornamental Skull, are rare enough that you'll probably only find two or three during the game (not counting the ones from chests) despite killing hundreds of the enemy that drops them. Special drops are also present in The Legend of Zelda: The Wind Waker, but each of them has completely different purposes.
Enemies in The Goonies games drop items like keys, hearts, and bombs.
In Super Smash Bros.. Melee, there is a 1 in 151 chance of getting Mew from a Poké Ball, and a 1 in 251 chance of getting Celebi. Disappointingly, they only appear and fly away, but reward you with a lot of points, and an alert after the match is done telling that you met them for the first time.
This also happens in Super Smash Bros.. Brawl, but with severely decreased chances of getting any legendary Pokémon at all. This being the case, however, most legendary Pokémon are much more lethal; Mew drops CDs, Celebi drops trophies, and Jirachi (who wasn't in Melee) drops a ton of stickers.
For all those die-hard completionists, Brawl's Subspace Emissary will be HELL. To get all the trophies in Brawl, you have to play Subspace Emissary, and have a trophy stand randomly drop during all the Boss Battles. When it comes to Meta-Ridley, it's incredibly frustrating - not only is there a time limit on the battle, but unless you have ABSOLUTELY PERFECT timing, the trophy will most likely drop into a bottomless pit if you're not fast enough. Luckily, trophy stands appear much faster in this battle.
Then there's the stickers in Brawl. There are 700 of them. 5 you get for completing challenges (and you can do the challenge over and over again to get multiples), but the other 695 of them are obtained completely at random; you have no way of knowing what sticker you get until you already have it (which is especially annoying if you're trying to get the stickers through Coin Launcher, since you can't save your coins to get one you know you don't have.)
The Tekken 6 Scenarion Campaign has this with clothing items. While you'd pretty much always get at least one item per stage, the effects they give off and how powerful those effects are is also random, so getting something useful was even less likely to happen than in most games with Randomly Drops.
A rare racing game case, the third Gran Turismo game has a prize system in which, starting with the late game beginner races, there are four cars that you can win. Too bad you can only win one of them—very frustrating since the endurance races are long as hell, you can't save in the middle of them, and there's a good chance that you'll get stuck with a crappy Renault instead of that Game Breaker F686/M.
First Person Shooter
Borderlands is the FPS equivalent of this (its initial pitch: "Halo meets Diablo"). It, too, has a list of super-rare (DLC-exclusive) weapons known as "Pearlescents". These super-strong firearms drop at a rate of 1 for every 60 orange (the previous highest-level category) items. Of course, they're a little more prevalent than you might think, thanks to a multiplayer glitch that allows for easy item duplication.
Gets to the point of ridiculousness in the sequel, with drop rates so low some players have to farm bosses over a hundred times just to get a specific item drop.
S.T.A.L.K.E.R. does this in a really silly fashion, sending you to collect the Eye of a Fleshie or Foot of a Snork. Which makes no sense—why fight potentially dozens of them for a single item to drop rather that just using your knife to cut off the body part from the first one you killed? What, did it take several tries to get it right?
Team Fortress 2 features a random drop system rewarding players with random weapons (and, very rarely, cosmetic items and tools) based on time played, up to a certain weekly cap. Prior to its introduction, the only way to obtain items was through class-specific achievements and milestones. While the first release of the system was quite shoddy (very rarely giving out items and often granting duplicates back when the game had no crafting or trading system), it has since had considerable improvements made to it.
Originally, the system was meant to replace the achievement system entirely, but after player complaints, the achievement system was re-introduced and the drop rate modified.
Early on, players attempted to game the system by using external idling programs which simulated gameplay without actually having the game client open (and thus using system resources) and playing, greatly magnifying the rate at which players could obtain hats. Valve brought the hammer down on these players by removing their items while rewarding more honest players with a golden halo hat called the Cheater's Lament and increasing the hat drop rate, greatly dividing the fanbase.
Later, the overall drop rate was increased by changing the system to decide when a player received a drop, instead of whether if a player received a drop, and a weekly cap of 8-12 items was introduced.
Finally, the system was edited again to curtail idling by only rewarding active players who meet certain conditions, such as responding to in-game drop notifications, only running a single instance of the game, and playing on VAC-secured servers.
Left 4 Dead 2 has random drops for Hazmat and Riot zombies. The Hazmat infected will drop Boomer Bile and the Riot infected will drop Tonfas. The odds of them carrying the said items are low but since they always respawn down the road, you are bound to score the items at least once per map.
The Passing campaign introduces the Fallen Survivor infected. Somewhat rare since they only appear at least once or twice per map and they can carry either a First Aid Kit, Pipe Bombs, Molotovs, or Pills and they can carry either one of the items or all of them. However, this immune to the sounds of the Pipe Bomb, have as much health as a Witch, has their head protected so making a head shot is harder, and they will run away if attacked. Because of the amount of items they can carry and their low encounter rate, Fallen Survivors also double as a Metal Slime.
Robots in Descent can release energy or shield boosts, or various weapons that your ship can use. The probability of the item appearing is always out of 16, unless a robot is customized so that a certain drop always occurs. Customization can also enter Impossible Item Drop territory— which generally happens with the unarmed Supervisor Droids, but other examples include coded "clones" of enemies like the Omega Spawn and Green Spider in Descent II, which look the same as their regular counterparts but sound different, are worth slightly more points and can drop missiles (usually Guided Missiles) that are bigger than they are and not part of their arsenal.
Hack And Slash
The Diablo games feature items that aren't just randomly dropped, but randomly generated from thousands of potential combinations of attributes, special abilities and base weapon types. Runes (items you can place into other items to make them better) are particularly glaring, with some high-level runes having such tiny chances to drop (1 in millions, and even that requires finding enemies even capable of dropping the runes in the first place) that most hard-core players have never seen a legitimate one (ones created by hacks, of course, are another matter entirely). In fact, one person apparently estimated that one has a better chance of getting hit by a falling plane that was struck by lightning than one does of finding the rarest rune. Nobody knows if that estimation is true, but you get the idea.
The rune example is fairly straightforward, but it can get much more complex: A base sword, for example, might have an inherent range of say 5 +/- damage and 10 +/- quality. So, just getting a "max" sword would take at least 15 rolls of that sword, of which, the top swords are also rare. Then, the top prefix is "Cruel," which varies between 200-300% added damage. The top suffix is "of Eviscration" which also varies by 20 points. It is estimated that maybe 1 sword has ever existed that was truly "perfect." You would need 10's of thousands of rolls to get a perfect roll, but you would probably need somewhere around 100 million of that sword to get 10k with that roll to even have a chance at the perfect stats. And then, there's the "Etheral" version, which is 1/3 as common as the regular version. Only 1 300% Cruel, Etheral, Elite class, 2 Socket sword has ever been found.
Diablo II includes many items that, when equipped, increase the odds of an item drop, notably socketing an item with perfect topaz gems. Some players traded for as much of this equipment as they could cram onto themselves, and went hunting; the Barbarian had an edge over any other character in this respect, because the optimum item-finding equipment package requires dual-wielding a pair of enchanted broadswords, which only the barbarian can do, and the barbarian had a skill that basically amounted to "trigger the random drop again".
Diablo III' allows people to buy gear with real life money...which prompted cries that it was ruined amongst people who mysteriously now actually liked farming over and over again for random drops of equipment knowing 90% of it was worthless and only good for bribing other players to run you through zones if you're lucky. Apparently they forgot the decades of complaining about "Farming" or "hunting" and receiving nothing but garbage.
Ninety-Nine Nights is a terrible offender in this category, with the final boss being almost unbeatable without an item which randomly drops (Or more likely does not drop) from one of the finite number of enemies within the last level, often forcing you to restart the mission hundreds of times over before it finally drops.
Final Fantasy XI has a couple items that are stupidly rare. Not only is there The Ridill (average drop rate: about one every 20 kills of Fafnir at best), but it also has Defending Ring (about one every six months) and Hauteclaire (about one every three months). Dynamis often falls victim to this due to the fact that every monster in a Dynamis zone has an extremely low chance of dropping one of many different armor pieces (which is made up by the fact that these zones contain hundreds of monsters). Many linkshells end up with a particular set of pieces that are rare, while three jobs (usually Beastmaster, Dragoon, and one job that is actually desired at first) tend to drop at a fast rate. And this is just endgame. Listing all the things that eat a ton of time due to ridiculously low drop rates would take up too much space.
Also worth noting are the respawn times on these monsters. Fafnir takes a whole day to respawn, the other two spawn every three days. And there are other groups competing with you. Even worse would be Voluptuous Vilma and Defoliate Leshy, which only spawn if other rare monsters are not killed for a long time. The existence of these monsters was unknown until a small group of players went onto the test server for a tournament and saw them.
Rarely do drop rates in Final Fantasy XI drop below 7%... except in Salvage. The premise of Salvage is that collecting 3 like pieces of equipment (3 mage gloves, 3 warrior boots, etc) from the ancient ruins of the Alzadaal civilization could allow a player to restore a piece of Salvage equipment, which constituted quite a bit of the game's Infinity Plus One gear. The first two pieces are generally easy enough to obtain, with the first piece (level15) being 100% and the second piece (level25) usually being around 25%. Then you have the third piece (level35)... If it happened to drop in the Silver Sea Remnants section of Alzadaal, chances are you're still looking for it. Or not, because they've almost all since been replaced with better and more immediately satisfying equipment.
Played seriously straight in MMORPGMapleStory. Monsters have a very good chance (roughly 50~75%) of dropping some money (Mesos) and an "ETC" drop unique to the monster (or monster type). They have about a 1-in-10 chance of dropping potions or material ores, a very rare chance of dropping equippable items, and an extremely rare chance of dropping scrolls (which are used to upgrade equipment) or throwing stars. A coupon in the game's cash shop doubles the drop rate of monsters killed by the user. It doesn't help that sometimes only one particular enemy drops a particular item. Or that there's no indication that a miscellaneous drop is needed for a quest you don't have. Or quests that ask you to get an item, but don't say what enemy drops it. Then there's the major bosses Zakum and Horntail, who are guaranteed to drop at least one Zakum Helmet or Horntail Pendant each time they're killed, it's how many that drop that's random. All of their other drops are subject to Random Drops.
The Malaysia exclusive map (guess what it's called) has somewhat broken drop rates- i.e. something around twice or thrice that of the original maps. This stacks with the event bonuses.
This aspect is where some quests become truly, stupidly hard. For instance, there's one quest where you have to find a little fairy's lost glass slipper. The slipper was stolen by the fire boar enemies in the mountains around Perion. No one is quite sure of the drop rate, but you can stand there and kill - quite literally - thousands upon thousands of fire boars and never see the item.
It doesn't help that they randomize the drop rate at least once a week so you can't even figure out what the drop rates are.
Worst of all is Nexon's "solution" to the botting problem that has plagued the game for years. Rather than implement ways to prevent such cheating, EXP and droprate is based off of character level, making it impossible for high-level characters to obtain items from low-level monsters.
Several dungeons in World of Warcraft include rare magic items with drop rates of under 0.01%. One instance, Shadowfang Keep, includes a set of items that possess a drop rate of roughly 1-in-7000. Previously Baron Riverdare's Deathcharger, an epic mount, was an example, but the drop rate for it was raised to 1% in the 3.0.2 update, also considering you can easily solo the Stratholme instance with a level 80 or even 70 character. Still, quite some work for some Bragging Rights Reward—and Blizzard loves doing that, especially for mounts. Sabertooth mount anyone?
Of course, there are also the "world drops"—rare items which have a very small chance of dropping from ANY monster of the given level range. Acquiring them comes down to pure luck. Or having a ton of money to spend on the AH.
In Wrath of the Lich King, high level leatherworkers need Arctic Fur in quantity both for buying and for making high-end patterns. Arctic Fur is randomly skinnable from any skinnable Northrend mob, with a drop rate more normally associated with the above-mentioned "world drops." Many patterns require more than two.
Arctic Fur and it's Cataclysm equivalent Pristine Hide, can be traded for with leather, but that doesn't mean it's any easier. Buying one Arctic Fur requires lots and lots of leather, so much leather that you'd probably get the Fur to drop while farming the leather needed to buy it.
There are also some items that are easy to get but useless unless you get the correct version. What is essentially one item can have about 12 different sets of stats.
Additionally, a huge number of quests require randomly dropping items that cannot be traded, and only drop if you have the quest. Oh god... How long does it take to find four hooves from a four hoofed animal? It's longer than you think.
There is a quest where the player must collect 12 raptor heads. If you think this involves killing anywhere near as few as 12 raptors, you've clearly never played World of Warcraft.
Hillsbrad Human Skulls. The listed droprate is a little off (Since they only drop if you have a quest to collect them) but the exact population of Hillsbrad that actually have skulls was about 35-40%. And you need to collect 30. Ouch. Fortunately, Blizzard finally made them a 100% drop. But still no fix for the headless raptors...
Prior to the Cataclysm expansion, a southshore alliance quest had a man request that you bring him 10 murloc heads. You rarely completed this objective with anything less than 25 murloc kills, at least.
The game eventually Lamp Shaded this with one of many items that drop irregularly from a specific group of mobs. "Surely enough, not every one of them is wearing one. Cowards!"
Another special case are drops from bosses that can only be encountered during an ingame holiday with a low drop rate. Not as bad as the above examples but the limit on the boss itself cranks it up considerably.
Two particularly aggravating examples are the Hallowed Helm hat and Sinister Squashling pet, two rare drops from the Hallow's End event. The items have three sources: the event's Headless Horseman boss with a 7% chance each, from a daily quest during the event with a 1.7% chance, and from an hourly repeatable interaction with any innkeeper for a 1.3% chance. Why is this example particularly bad? Because acquiring both items is requisite for the achievement "Sinister Calling," which is in turn requisite for the holiday's meta-achievement, which is in turn requisite for the meta-achievement "What a Long, Strange Trip It's Been" which requires a year, minimum, to complete anyway, turning an already arduous task into a Luck-Based Mission.
Blizzard likes Randomly Drops so much that they were included in the Trading Card Game. The so called loot cards have codes that can be used ingame to acquire one of several special items, although most of them are pure flavor.
Farming for dragon whelps. At a 0.1% drop rate off only certain monsters (some of which share spawn points with monsters that don't drop the whelps), it can be painfully boring.
Phantasy Star Online's most powerful weapons often have drop rates ranging from 1-in-72 to 1-in-22000. Add that to the fact that the 1-in-22000 monsters usually only show up singly, and only in certain map variations...
And only for certain characters, as a character gets 1 of 12 possible dropcharts permanently assigned to it upon creation based on the character's names, class, and even gender, with some items having a 1 in 299594 chance from only 1 chart, from 1 monster, that can only be found in 1 area, with the monster being the rare form of an already rare monster.
Beaten to death in Anarchy Online, an MMORPG where you will find that some of the most powerful and sought after items in the whole game (and since this game deals also in quality levels per any given item, in that as well) are so rare, they could be the poster child for this trope. The number of times that one specific item, the Sparkling Scimitar of Spetses (a stupidly rare item dropping from a semi-boss from the 2nd hardest area in the known game) is so ridiculously rare that it is counted among the forums. The numbers are kept as to which dimension (of the 3 this game has) has dropped how many... at last count, it was STILL IN THE SINGLE DIGITS for dropping after at least 3-4 (maybe longer) years of play in the game that allowed the zone. Though if you want similar horror stories, ask hardened, end-game players about the Spirit Shroud, anything regarding Alien boss drops, or really anything valuable in the game in question. As a result of this, of course, Adam Smith Hates Your Guts.
Kingdom of Loathing uses this extensively. Also, certain quests require you to get items from standard enemies, which will never drop those items until you get the quest. The dread of this class of random drop is mitigated by the ability to buy some of them. But by no means all. This has been justified by the creator as "you did not know it was important so you didn't pick it up" which, considering the item is a twig is believable.
And let's not forget the game's "ultra-rares"—the player base STILL isn't sure how it works. The game's fansite says your best bet for getting, say, a 17-ball (erases your Elemental Rock-Paper-Scissors worries) is to save your money.
Then again, the game also lets you play with the drop percentages. It's not much, but the game's guides do show how to maximise item drops.
Most of the very-rare drops in Kingdom of Loathing are just icing on the cake for most players, which is helpful; most of the best equipment in the game is acquirable by playing through a "hardcore" ascension. A few rare random drops usually become the purview of Speed Run players who use them to shave a few more turns off of their next game.
Apparently, it is possible on a Bad Moon ascension to get a rare item to drop, only to have a nearby kitten bat it into a nearby sewer grate, meaning that you don't get it.
Everquest had some mean ones. One otherwise uninteresting newbie zone had a high-level halfling that spawned every few days in a random location, disappeared after two minutes whether anyone killed her or not, and had a one in eight chance of dropping a very expensive item.
In Everquest 2, in most zones, monsters will drop an "exquisite chest" (a chest containing the best kind of treasure, Fabled) 0.0126% of the time. Of course, which Fabled treasure drops depends on random chance and which monster dropped the chest...
A staple of Ragnarok Online. Each enemy has a 1/10,000 chance of dropping a "card" (with rare exceptions like porings at 1/1000) which can be permanently placed into a "slotted" weapon or armor, which also have an extremely rare chance of dropping. The cards give bonuses to you when you wear armors with a card equipped. They range from completely useless in the case of most ordinary monster cards, to boss cards which have downright Game Breaking stats such as immunity to spells and abilities. The catch is, since bosses only respawn once per hour in one location, if you were to kill a boss every hour on the hour for a year you would only have a 58% chance to get their card...
Due to the way the RNG works in this game, it's actually 1 in 5000. (The RNG can actually hit 0, giving stuff a .01% higher chance to drop.) There's cash shop items to increase this further.
In Warhammer: Age of Reckoning, although there are still random drops, when you get a quest to get, let's say, 10 wolf eyes, at least the game have the decency to give two eyes to most wolves, and no quest has a <1 drop ratio. You also get fairly good items from influence and even better ones for cheap if you have renown, so the rare-drop ones aren't all that needed.
zOMG! loves random drops. Your basic things like gold, loot, Power Ups, and the occasional recipe drop. However, there are several more unorthodox examples. Charge Orbs (the games version of experience points) are a random drop as well (though quests always drop them). Rings (which represent skills) are also random drops. Thus, your progress through the game is reliant on random drops. You can, in theory, buy high leveled rings from the marketplace to max your charge level. However your drop rate is affected by your charge level. The higher your charge level in relation to the monster your fighting (represented by a color system), the lower your drop rate. This is complicated by the fact that certain quests (most notably the Totem Collection quest at the Otami Ruins) ask you for specific loot items, which you have to get through a random drop. Buying and trading them doesn't work. Complicating things further, drops are automatically rewarded to players to prevent fighting. Thus, drops cannot be delegated based on who needs them for quests, making this pretty much a Luck-Based Mission. (Luckily, luck is a stat, albeit an invisible one). And finally, by crewing with someone radically more powerful you actually hurt your drop rate by a significant amount. Trust me, this game is harder than it looks.
On the main site itself, there's Chance Items that, when opened, can net the user anywhere from cheap commons to rare, exclusive items that usually go for millions on the market. The rarest of these items is almost always a cute animal companion for your avatar.
City of Heroes cheerfully chucks all this out the window—pretty much any enemy that gives you experience points also has a chance of dropping pretty much any loot (within certain confines—mostly level ranges and loot types, neither of which prevents them dropping the 'good stuff'), although more difficult enemies have a slightly higher chance of dropping higher-quality whatevers.
Ace Online goes almost into orbit with this trope: In addition to a normal Item drop table, rarely-spawning gold-named mobs have a supplementary Gold Mob Drops table, and Boss Mobs have their own Boss Drops table. The latter two are not affected by the regular item drop bonus given by regular Happy Hours (but are affected by Nation's Growth and Mothership Victory happy hours).
In addition, Event Mobs and the aforementioned Gold Mobs have a (slim) chance to spawn whenever you kill a normal monster. Happy hunting.
It even ups the ante with itself with the much vaunted Boss Armors. Each Gear has special armors from a specific boss. Now let us list the prerequisites on how to obtain it:
Defeat the boss and get the drop. Problem: Bosses rarely spawn more than three times per 24 hour period, and the drop rate of said armor is 0.002%. And it's hard since it's a boss. And this drop is an unfinished version, and most of the bosses spawn in areas where the two opposing nations can access, which is why some Boss Hunts end up as PVP Camping Contests.
Find a corresponding item to combine with the unfinished version. Problem: said drop, although more available than the bosses also has a low rate: 0.008% rate.
Combine the two items, which has a 50% chance of failing. If you fail, both items are, yep, Lost Forever.
0. The zeroth prerequisite to these is that you must be above a certain level to equip this in the first place.
The Episode 3 Part 1 however, makes it somewhat easier; there're three bosses in Pandea Maps that can drop any one of the unfinished boss armor. The corresponding item has the same quirk. There's only one slight problem; the entire Pandea maps are Scrappy Levels made of aggro, aggro, and... more aggro. And more aggro.
Even kid-friendly MMORPGS like Toontown Online have this. Many "Toontasks" (quests) have you go fight certain kinds or levels of Cogs (the main antagonists) to get certain items. Even worse is if the type of Cog that drops it is found exclusively in one of the * shudder* Cog Headquarters. Here, it's downright evil because you only get items and experience points that you earned at the end of a boss fight. Including defeating the Big Bad after destroying all his Mecha-Mooks (Technically, they're all Mecha Mooks.) If your connection drops out, or you lose all your Laff Points (hit points), you don't get anything. And if you failed by droping to 0 LP, you lost all your gags (weapons) as well. Horrifying if you had just earned a Level 7 Gag (which you can't buy; after you max a type of gag, you get one every 500 EXP). Some tasks are more benevolent versions of this trope, only making you go fishing (yes, fishing) at a pond in a certain area to get X number of whatever item was requested. (The game gets really mean by coupling this with other sub-tasks, mostly involving the meaner example of this trope. No more Cashbot Mint fights, please...)
Almost every monster in RuneScape has random drops on death, even those with 100% guaranteed drops (which are usually some variant of bones or ash). This is usually coins (or equivalent local currency), but a large number of monsters have access to the Rare Drop Table, which has more valuable drops on it. There are also monsters that can drop a nice Rare Random Drop.
A specific type of rare item drop in RuneScape is the Champion Challenge Scroll, these are dropped by specific monsters and are a challenge issued by that monster's champion fighter; oh and they have a drop rate of at least 1/5000. Collecting at least 1 scroll is required to unlock a music track to unlock the Complitionist Cape; collecting all 13 challenges, plus 2 formally issued challenges obtained after collecting the original 10 scrolls and the additional 3 scrolls that were released later, are required for the Trimmed Completionist Cape.
In "Dynasty Warriors Online", random drops are interesting. How it works is 3 LAYERS of random drops, but done fairly so you can actively seek out such drops without going "please, lord let this be it or kill me. but not both." The actual fighting aspect is done via arena setup. So you start a room, up to eight people (4 vs. 4) live players can join, but you can just go with a Dumb computer in it's place, and there can be as many as 7 comps in a game. In the field, there are named officers that appear to be mooks but have a slightly more unique look and are stronger than mooks. They will drop one of three things. Random layer one is what officer has one of the 2 items on that side, there are four total but unless you can kill friendly players then you can only get two. Layer 2, for each of those drops there is a random chance that you will get either an armor/clothing piece, or a weapon that you can pick up during the battle. Layer 3, after the battle, and if on a choice above newbie level pairings then losing means you also lose all found items, but the enemy doesn't gain them, then there is a random chance what the weapon/wearable will be, and of what quality.
Depending on how many weapon updates there are, the chance that you get a certain weapon lowers but there are no "rare" weapons, all weapons have a chance to show up. Armor is slightly different in that you must fight a certain faction to have a, or possibly a greater, chance of getting certain armor.
Items, actual items that get used up after the battle, do have a more % chance of finding then weapons. However, even the most rare can be found in game via simple habit of getting on every day, or via buying.
Dungeons & Dragons Online, of course, also has these. They can be found by killing monsters, breaking items, or more commonly by finding sparkling objects (cabinets, alters, plants, etc.). There's also the loot system for chests; every time you open a chest, there is a random chance of between 3 and 10 items appearing that depend on your level and the difficulty of the quest. The weapons and armor in turn are generated in such a way that, once the base item is generated, it has a random chance of having certain effects and attributes. Quest rewards can be random, but many give you access to the whole list of available items.
The Lord of the Rings Online has many quests of the form "Bring me 12 craban (crow) eyes." There used to be an astonishing number of blind crows flying about. The drop rate has improved with later updates, but they're still all one-eyed at best. Another quest requires wolf fangs, and you may be excused for wondering exactly how that fangless wolf you just killed was biting for so much damage.
Real Time Strategy
Played absurdly straight in Dawn of War 2. Space orks, space elves and space bugs all have similar chances of dropping ancient Space Marine equipment neither of them should have needs for or (in case of Tyranids) means to carry.
Kingdoms Of Camelot on Facebook is this way. You have a random chance of getting Crests or Seals from wilderness attacks, and once enough are accumulated, you can start another city. Incredibly annoying if you get the crests out of order; you can have all of them but lack crests for an earlier city deed and have to wait until you get the missing ones to get both cities. There is also a chance of items from Dark Forests that go toward crafting items in the Fey Tower and gaining the seals needed for the Fey City. Additionaly, Throne Room items can be gained by attacking other players' cities.
Wasteland Empires has this as well. You attack other players' colonies and hope for random drops of items needed to build up your own. Good luck hunting down higher level items like Old Books, though. It's not easy.
In Nethack, enemies will randomly drop their own body. Bodies are food. If you're hungry and the wild boar you just clubbed does not drop a dead wild boar, you may starve. Only large monsters like rothes and Leocrotta are guaranteed to leave a corpse.
For items, this trope is mostly averted. Monsters always drop their entire inventory on death, so when you kill a spear-wielding elf you can count on looting an elven spear. The "mostly" qualifier is because there's a very small chance of a monster dropping a item that wasn't there before on its death, so a centipede just might drop a broadsword.
Ancient Domains of Mystery. Nearly everything can be randomly dropped or pickpocketed, even artifacts. Unfortunately, many items that are important for various quests (notably the amulet of life saving) are also random drop items. Where the Creator really extracts the urine is when you are required to find a boar skull as part of the Ultra ending quest. Said boar is only encountered infrequently, is in the highly-dangerous overworld and even then rarely leaves a skull. Low-to-mid-level players frequently starve to death or spend 60-320 game days trying. Higher-level players resort to dooming themselves to increase the encounter rate, or hunting for an item that grants one wish (also only available by random drop, and extremely rare).
The boar skull is much easier to find than the scroll of danger needed for the same quest. Boar skulls about a third of the time from giant boars, so any character over level 15 can find them pretty easily. You can go through the entire game twice and never see a scroll of danger.
Role Playing Game
Final Fantasy IV. Pink Tails. They are held by one enemy, found in one room, with approximately a 1-in-64 chance of encountering it and a 1-in-64 chance of dropping the proper loot once defeated — and that's the only way to get the best armor in the game. For those of you who didn't study math, that's a whopping 1-in-4096 chance per encounter. This is ameliorated somewhat if you've accumulated a stockpile of Alarm items, which trigger encounters; in the room in question, they trigger an encounter with these particular monsters. This is made worse in the DS remake since the newly added optional bosses are impossible/near impossible without said armor... on all party members. Also in the DS version are Rainbow Puddings. Some people have attempted three days with none of it dropping... and some people get tons of pudding without even trying.
Additional...fun in relation to pink tails. The only way to find the monsters that drop it in the DS remake is to use an Alarm item. Otherwise the room is completely clear of random encounters. So, at least now you have a 100% chance of encountering the enemy, right? Well, you now have a 1/64 chance of the Princess Flan dropping any item AT ALL, and a 1/64 chance of it being a Pink Tail. So the odds are the same (1/4096). But you can only hold 99 Alarms at a time, and each time you need more you have to trek ALL THE WAY OUT of the dungeon (or teleport), use your airship to reach the one shop in the game that sells them, and then walk all the way back to that one room. Remember, every 100 encounters, you have to spend 10ish minutes walking, even with the teleport and no random encounters. And the chance is 1/4096. Have fun spending on average 6.5 HOURS walking back and forth per tail. If you don't teleport, or run into lots of encounters, expect 13 or more hours just walking. And that's not even taking the fight with the flans into account.
Most enemies in Fallout: New Vegas have a random chance to drop various items, either crafting items or Vendor Trash. However, they re guaranteed to have the equipment they wield in their inventory.
Its sequel, Final Fantasy IV: The After Years, seemed to be guilty of the above as well, but then it was discovered that thanks to its cellphone roots, its RNG is comparable in Golden Sun in its simplicity and people have already found methods to get pretty much any and all 1/256 items every time. There's also items that increase the droprate normally, and change that drop to the next item on the rarity list. Due to the way this works, you'll be seeing a lot of supposedly rare items and zero common ones just by playing the game normally with the best items of each category equipped.
Played straight in the PSP collection, where the random drops are actually random again, but averted slightly in that it's more likely you get rare item from the Challenge Dungeon boss chests that're randomized and the worst item you can get is an X-Potion: however, you can't get any extra copies of any of the items, including Adamantines that're used to trade them for parts of Armor of Invincibility at the end of the game.
Final Fantasy V, like the other Final Fantasy games, has several rare drops. The Tinklebell is the most annoying, and belongs to Twintania. It's technically a 1/16 drop ratio, but Twintania's drops change based on whether it's in Normal form, or if it's in its Gigaflare form. The Normal form is the harder to kill of the two, and is the form that drops the Tinklebell.
Final Fantasy VI subverted this trope in a clever way. Every monster in the game had common and rare drop items. The rare drop has a certain (small) percentage of dropping. Otherwise, you get the common drop guaranteed. Most monsters did not have common drops, but some monsters (especially bosses) were guaranteed to drop certain items because they had the same item as both common and rare drops. (Barring a certain glitch that makes the second Behemoth Suit you're supposed to get unattainable.)
Final Fantasy VIII is an unpleasant offender, too. Several of the items required to get Quistis's best Blue Magics (Shockwave Pulsar, for example, though Ray-Bomb is a worse offender) require either hours and hours of card-playing, at least a couple hours of stealing from enemies, or (in the hideously egregious case of Ray-Bomb), attempting to steal a 12-in-256 drop from an uncommon monster.
Final Fantasy IX has a variation on one of these: Eiko's Fairy Flute can stolen from Hilgigars on disk 2, a full disk before it becomes available in a Mogshop. Not hard - equip Bandit and spend a few turns trying to steal it, right? Wrong. It is quite the hardest item to steal in the entire game, and Hilgigars isn't an easy boss, either. Most walkthroughs advise just giving up on the Fairy Flute and buying it later. Not necessarily a random drop, but the difficulty and time required in getting the item definitely qualifies.
Final Fantasy XII took things to somewhat ridiculous length: not only does every monster have common, uncommon, rare and ultra-rare random drops (and a fifth class of drop that requires you to purchase a 'monograph' describing that class of monster), but also (different!) lists of random steals and 'poaches'. Crafting Tournesol, the game's Infinity+1 Sword, requires multiples of the rarest loots from the rarest monsters.
The vast majority of treasure boxes in Final Fantasy XII were random drops; sometimes, the chest wouldn't be there, and most of the time, all the treasure you'd get from most boxes was a paltry sum of Gil. Worse, most of the chests that were fixed caused the Infinity Plus One Spear to become ONLY a random drop, with a chance of 1-in-1000.
The Chest that contains the aforementioned spear is in the Bonus Dungeon and has a 10% chance to be there. The Spear has a 1% chance of being in that chest. It can be obtained through this even if you've already got the one that's in the fixed chest in another Bonus Dungeon. If you're INSANELY lucky, you can get 6 or more Z. Spears allowing you to outfit every character in the game with the Best Weapon in the game.
Final Fantasy XIII adds the notoriously uncommon Trapezohedron to this growing list of epic loot. The Traps are extremely rare items that only drop once in a blue moon from an Adamantoise, which is basically a Bonus Boss for all intents and purposes - and one that requires extensive planning, preparation, and Level Grinding to defeat. (Or Death spamming, if you're willing to put up with the antics of the Random Number God.) Many players have killed several dozen of these absurdly tough enemies without getting a single Trap, which is needed to upgrade your Infinity–1 Sword to an Infinity+1 Sword.
In the Rune Factory game series Item Crafting is a major part of the game. To create the vast majority of powerful equipment and potions requires many battles with the various monsters, to get the Randomly Drops components you need.
Persona 3 has Elizabeth's requests, in which she usually asks you to kill a specific enemy and bring back a number of parts from it. The trick is that if you don't kill the enemies with the protagonist, the item drop rate is extremely low. And even if you do kill said enemies with the protagonist, there will be a few times where you'll kill five of the same enemy in one battle... and get nothing at all.
FES corrected this: if you kill at least one monster of the required type in a battle, you'll always get at least one item of the required type, guaranteed, though at the expense of other possible drops.
Alter A.I.L.A. Genesis: In the core of the Orbital Prison, there is a chance that you will fight watermelon enemies that use a countdown. They drop Enhancer ABC's (Improves all stats except speed) and they will ALWAYS drop them. The problem is the encounter rate.
EarthBound. Its 1-in-128 items have become the focal point of several fan quests, as numerous gamers try to get them all. In fact, one character's only weapon that doesn't lower his offense, the Sword of Kings, is a 1-in-128 chance item. and when you defeat the boss of the dungeon it's in, the enemy carrying it never appears again.The Gutsy Bat is found in the area right before the final boss, so it'll only be used against Giygas. The broken antenna/Gaia Beam is dropped by an enemy that explodes upon defeat. The Magic Fry Pan is the simplest to get; killing a dinosaur. At least after hunting Starman Super for the Sword of Kings, Poo can make use of it for a long time.
Mother 3 is a bit nicer, with a 3% to 5% chance of getting good weapons from certain enemies.
MOTHER has a 1/16 chance of dropping any item from battles.
The Breath of Fire series. Numerous examples of this. In fact, Breath of Fire 3 features a rare enemy, the Goo King, that has a 1/256 chance of dropping a GooKingSword (1/128 if the chance is upped), which incidentally is (in raw power) the best weapon for the main character. This item is so rare it has become a running gag that it's really a hoax and not actually in the game.
Pokémon has the unique problem in that the frustration-causing random drop is more often than not the Pokémon themselves. Some appear very rarely in the wild, with 1-in-20 odds or worse. The frustration is compounded by the fact that you have to weaken these monsters without defeating them (and, sod's law, you'll kill the Pokemon you spent so long finding with a random Critical Hit), as well as hoping they've got the right gender, nature, ability, IVs...
This is compounded in the case of the aptly-named Chansey. They're one of the most common features of the meta-game and tournaments due to their evolution's usefulness in battle. The teeth-grinding part is that they're notoriously hard to find in the wild. They're found in two areas in the most games, at a rate of five percent. This wouldn't be so mentionable (many of the mons have this annoying characteristic) if it weren't for the fact that one of the most useful items in the game, Lucky Egg, is ONLY found on wild Chansey, at a one-in-twenty rate. Crunching the numbers, that's a 1 in 400 chance of getting a Chansey with a Lucky Egg. You want that item, you're gonna be spending a whole lot of time working for it. Ironic, considering Lucky Egg multiplies experience gains by 1.5 on a single Pokémon, meaning the only reason to go after it is if you want to save time. Luckily, later games have a variety of ways to make specific-drop hunting easier; if you're dedicated, a few minutes on Bulbapedia will tell you more than you ever wanted to know about it. In the GenerationV games the Lucky Egg is outright given to the player by Professor Juniper as the player proceeds through the story. Needless to say fans were overcome with joy.
Another Pokémon that deserves a mention is Feebas. This fish isn't so incredible at first and you need to evolve it in order for it to be useful (this is a tedious task in itself) but finding that Feebas in the first place is going to eat up a lot of time. It can only be found by fishing, but get this, it can only be fished up on certain tiles. Between 4 to 6 tiles out of hundreds, depending on the game. And these tiles are randomly generated and are prone to change. Once you've found your Feebas tile, try to catch a female one, or a Ditto if you're not playing Ruby and Sapphire, so you won't have to find one again.
There's also Munchlax. Originally the only way to obtain it (without trading a Snorlax from another game and breeding it) was through Honey Trees. There are 21 trees that you can spread honey on. Of these 21 trees, only 4 of them have even a chance of having a Munchlax. These are assigned randomly at the beginning of the game and you have no way of telling which ones are Munchlax trees until you actually catch one. Each tree also has 2 of 3 different possible drop charts that vary from tree to tree. The third set can only be used by Munchlax Trees and has a 93% chance of generating a Munchlax. Bad news? There's only a 1% chance of a Munchlax Tree using the Munchlax chart. Also it takes 6 hours after slathering honey for a Pokémon to appear, and messing with the DS clock doesn't work. And the Pokémon you find is set once you slather honey, so saving right before you check the tree and restarting won't change anything.
Given this horrendous process it's no wonder that virtually every player went the easy route and transferred a Snorlax from their Generation III cartridge into their Generation IV cartridge and just bred a Munchlax. One would be hard-pressed to find an actual person who caught a Munchlax through the honey-slathering method.
Pokémon Black 2 and White 2 have Hidden Grottos, which in a sense function similarly to the honey-slathering mechanic. For every 255 steps the player makes, there's a 5% chance that a given grotto will generate something within it. 80% of the time, its an item, and usually then, it'll be Mulch (though rarely it'll be a useful item). The other 20 percent, it'll be a Pokemon with a Hidden ability (a special ability that isn't usually available during normal play). The Pokemon that are found here vary from grotto to grotto, but usually the ones with amazing hidden abilities would be the rarest ones... Which will only appear 1% of the time. The most insidious part is that the gender ratio for these Pokemon are usually skewed to favor males, since only females are able to pass hidden abilities in the Gen V games.
Oh, but that's not all. This isn't technically a drop, but if you want a rare, Shiny version of a Pokémon, with a sparkling intro and an alternate color, you have a one in 8192 chance. By the way, Legendary Pokémon and starters can be Shiny as well, so start breaking in (or outright breaking) your soft reset fingers! Luckily, like the item example above, Generation IV introduced ways to boost this probability.
Don't forget the Pokérus! It behaves like a virus (once your leading Pokémon has it, it can easily infest everyone else in your party, etc.) but its effects are very beneficial. Without getting into stupidly hardcore hidden values in the game's deep arcane math algorithms, suffice it to say that you want the Pokérus. Too bad that any random encounter you finish has a 1 in 21,845 chance of giving it to you (in Gold and Silver). Luckily you don't have to catch it for it to spread, just battle. More luckily, now that you can trade online, it's very easy to achieve as you only need one and you're set for life.
The enigmatic Mirage Island of Ruby/Sapphire/Emerald! Every day a number between 0 and 65535 is generated. In order to access the island, you have to have a Pokémon in your party with a personality value that matches the number of the day. And the Personality Value of a Pokémon can be anywhere from 0 to 4,294,967,295. The only thing worthwhile about Mirage Island is a particularly rare berry tree.
Oh, and then there's Pickup, the ability to add even more random drops in your life. Basically, there's a 10% chance that a Pokemon with the ability gets an item after a battle. In Gen. III (the first games where Pokémon can have abilities), it always culled from the same list—resulting in a Disc One Nuke if you got one of the more rare items early (like a Nugget or a Rare Candy). Later games balanced it to make the list level-dependent, removing the Disc One Nuke status but adding a reason to level grind fairly weak 'mons. The potential rewards? Greater chances at getting a Rare Candy, some otherwise-rare evolution items, and the rare chance at acquiring items otherwise Too Awesome to Use. Plus, you always have the chance to get the item—sure, the odds are astronomical, but there's the chance your level 100 Ambipom can find five Earthquake TMs. In a row, even.
Thanks to the addition of natures, getting the best possible specimen can turn into this. There are 25 different natures, so that's already a 1-in-25 chance of trying to get the one you want. Then there are Individual Values, which can range from 0 to 31. Rerolling these to get decent values makes the odds even worse. If you want to get perfect IVs, the best way would be breeding. In the best case, two IVs would be randomly generated, and the odds of getting a perfect value on those would be 1 in 1,024, which combined with getting the nature you want would be 1 in 25,600. Good luck if you're trying to get them with a wild 'mon.
In Wizardry 8 enemy drops and chest contents are determined when loading an area. So after a 15-minute fight, if the monster doesn't drop Excalibur, you can't just reload and fight again. You have to reload from before you entered the area, then make it all the way back to the monster, then fight it again.
Both Golden Sun games have rare weapons and armor that drops from certain monsters across the world, and since store-bought equipment is horribly mundane in these games, acquiring this equipment could certainly be handy. The problem is that each item only has a 0.4% chance of dropping, upped to 1.6% if you kill it with a djinni attack of the correct element. However, given the rather simplistic nature of the random number generator in both games, it's possible to fix encounters to up the drop rate to 100%. Guess which method most sensible people pick?
Don't forget that some randomly dropped items can be forged into new, powerful equipment. A whole range of different equips per item, actually. How does the game decide which you get? Randomly, of course!
There are also the slot games that, while not necessarily "random", are a total pain to predict and give you some of the best stat-boosting items in the game.
Unfortunately, the RNG of Golden Sun: Dark Dawn is much harder to manipulate, which may have been deliberate on the part of the developers.
Averted in Shadow Hearts, where enemies simply don't have rare or valuable items to drop. This has the interesting side effect of averting Money for Nothing - since you aren't going to get much out of the enemies but money, shops and the items within become more important.
The World Ends with You seems to be initially guilty of this, and the game blatantly taunts you with drop rates that ultimately go as low as 1/30th of a percent. However, this doesn't matter much as you can initially increase the drop rate by as many times as your current level in exchange for a lowered maximum HP (i.e. your current level is currently 30, you can drop it to 1 to multiply all drop rates by 30), then further increase it by chaining together battles and multiply it with the number of battles you chain in exchange for increasing enemy stats for each successive battle. As if that wasn't enough, there's also expensive and relatively hard to get food items you can consume to permanently increase your base drop rate by 1 or 3. Thus, in the end it's not as much of a question of lucking out with ridiculously small odds as it is a question of being able to win a battle with odds heavily stacked against you, which is far more acceptable.
Not that heavily stacked, though — by the time the rarest drops become available, you're going to be at a high enough level that losing 20 or 30 levels doesn't hurt that much, even on Ultimate difficulty. At that point, chaining five or six battles (which doesn't increase enemy stats that much) will give you a good chance of obtaining even the rarest items.
If you're planning on time-attacking, raising your base drop rate is a very bad idea; instead of finishing the battle once you deplete the enemy's HP, you have to wait for your dropped items to spiral around your characters and get collected.
While not technically drops, Yume Nikki has random events throughout the game with varying percentages of encountering. In the case of the infamous Uboa event, the randomness of it actually heightens the suspense and makes it more terrifying when it appears.
In Mega Man Battle Network, many of the games require you to have used each Program Advance at least once for 100% Completion. The problem? Doing so requires you to have exactly the right chips to form it in the exactly right code, which can usually only be obtained from random encounters, or if you're really a masochist, spending a couple hours at the chip traders. Even if you have the right chip and have figured out the Advance, the odds are pretty good that the chip you have is the wrong code, and many of the codes you need for them are the ones that are only dropped at a particular busting level by a particular enemy in a particular location, who generally appears together with other enemies that drop things you don't want.
This is especially annoying in Battle Network 4, where you're forced to bump up the difficulty level which in turn levels up the enemies. Good luck getting the Level 2 Chips once you hit difficulty level 3, they're reduced to rare encounters and only in one or two locations.
And then there's the Battle Mystery Data, items that appear on one panel and have 1 HP, and it must survive to get the item. Most of the time, these are placed in such a way that you must risk either the data or damage to make sure it survives. Then there's ShadeMan Omega's EvilChip, which can get randomly destroyed if the bat he turns into after any 10 HP or higher attack goes in that row - or you destroy it with a missed shot. At least LaserMan Omega keeps his attacks toward you.
And in Mega Man Star Force 3, there's "Illegal Data Aquisition". Overkilling random enemies or attacking bosses with a specific subset of cards (Non-elemental, non-time-freezing) and then not shifting into your super form will allow you to receive a random drop after battle. And it really is random. You could get almost any standard card in the game, or a bug frag for trading; but most importantly you can get Illegal Cards that are unobtainable every other way in the game. And there's more illegal cards than there are normal battle cards! The smallest pool of random drops for any enemy in the game, however, goes to the already stupidly rare and powerful v5 Bonus Bosses, and that's roughly 30 possible drops; most enemies in the game can drop upwards of 80 different battle cards via IDA, so getting what you want can be extremely frustrating, nevermind that most of the ones you do want, you'll want 5 of!
Refreshingly averted in Gothic. If the player kills a wolf, and he has the 'skin wolf' skill, he will skin that wolf. Of course, this doesn't stop people wondering exactly how much skill it would take to pull the wings off a giant mosquito, or why wolves only seem to have four claws, total.
In addition to randomly dropped items, Valkyrie Profile Silmeria has randomly dropped party members; when you recruit an einherjar, unless it is plot-critical, the game will pick one at random from a list, usually 2-3 possible characters to a recruiting item. Highly annoying if you want to get specific spells.
Dragon Warrior 7 for the Playstation uses this one frequently. If you want a certain type of monster heart, you must play Memory at the casino or keep fighting monsters until one of them drops a heart. Otherwise, you can never transform into certain monsters.
Monster Hunter: this is one of the main extra difficulties in the game, for almost ALL kind of loot and carves. Examples include:
The Lao-Shan Ruby item. This item is necessary to craft some very good armors and weapons, and is only given by a monster named the Lao-Shan Lung. Unlike many others in this page, the odds are more decent - only slightly below 1%. Not so bad, except the Lao Shan Lung is a huge boss that always takes about twenty minutes to kill, each time (since it's scripted that he can't die until he reaches a certain point, his health will stop going down no matter how much you attack it). Twenty minutes per attempt, with a 1 in 100 chance. Other examples are Rathalos Plates and Rubies, and Heavenly Scales (which, by the way, you need several of to make anything from them), and it's easy to see why one of the chief concerns of the Monster Hunter fanbase is finding the best ways to kill the enemies as quickly as humanly possible.
Then there are the Big Elder Dragon Jewels in Unite, which can be the hardest items to get in the game. They are dropped by G-Rank Elder Dragons with a 1% chance (or in Chameleos case, 2%). What makes these more frustrating than other extra-rare items, such as Heavenlies and Rubies, is that you must kill the dragon in case to even dream of obtaining it, and every Elder Dragon takes 3 or 4 quests to be slain. And some of them, like Teostra, are not exactly easy.
Regarding the ancient dragons, there's Ceadeus and it's very difficult to get Deep Dragongem, the same could be said of Alatreon and its Azure Dragongem.
Uragaan's Rubies are very difficult to get as well.
Portable 3rd takes this trope to an extreme with the introduction of Guardian Stones, which has different skills and point allocations each time you mine a raw stone for examination. Granted, you may have limited control over those skills you may get (see various analyzation sites), but not their values. For example, a popular (and rare) stone with Sharpness 4 and ESP 10 will only appear as the highest rank stone., with a minumum of 0.019% chance, at best 0.944%. It becomes worse when you can't control which type of raw stone you may get from mining (most times it's not even a raw stone to start). Good luck mining.
Carried over for the Cross Over in Metal Gear Solid: Peace Walker. Rathalos drops plans for the Taneshigama, one of the most useful weapons in the game, and Tigrex and Gear Rex drop parts of the most powerful Co-op weapon in the game. With a 1% chance. Enjoy your grind.
Kingdom Hearts has randomly dropped synthesis items, each one normally dropped by 2 different monsters. These items were needed to make the Infinity Plus One Sword, but it is almost completely averted due to the amount that you can increase the drop rate of these items. (Even the rarest synthesis item could usually be found with a 1:5 ratio, aside from those that only came from chests)
In Kingdom Hearts Coded, you can unlock a special cheat that allows you to multiply the drop rate of the various command chips dropped by enemies in exchange for lowering your maximum HP, up to 16 times its normal rate. The difficulty level of the game also affects enemy drops. A few of the game's strongest enemies will drop stat-boosting chips on Critical mode, the highest difficulty.
The Elder Scrolls almost entirely averts this trope. Every item needed for a main line quest is always fixed, and even in Arena and Daggerfall where sidequests are randomly generated the item will be placed the minute the quest is accepted and won't move until you get it. In Morrowind and Oblivion, which have no random quests, ALL quest items and artifacts (and even non-artifact unique magic items) have fixed locations. Then Shivering Isles came and introduced a quest that required you to collect half a dozen random drops. Needless to say this is the quest that usually stays uncompleted.
Lost Odyssey has Ring Assembly components randomly drop, but thankfully nothing important. Then the Seeker of the DeepExpansion Pack had to go ruin that by including some ridiculously good, ridiculously hard to get randomly dropped accessories.
Summon Night Swordcraft Story 2 is notorious for random drops, especially after you finish the main game. You missed a rare item in the story? No worries, you can get it again from random monsters in certain areas! ...maybe! And since the monsters that drop the valuable materials you need are so rare already, it makes completing your Weapon List take forever to complete!
This happens in Live A Live, with the Cola Bottle, a powerful accessory and attack item. It is a rare drop from a Guide Dang ItBonus Boss, which means that it is quite possible for the player to not realize that the aforementioned boss can even DROP a different item to its normal drop.
Also of note is Feminophobia/Gynophobia, who has an attack that causes Drunk, whoch makes it That One Boss... Unless you get a certain drop (with zero hints) that protects from the Drunk status. THEN it's much easier.
Raidou Kuzunoha vs. King Abaddon features Ukemochi liver, a useless item that's necessary for exactly one sidequest, which in turn is necessary for 100% Completion. The only way you can get it is by donating money to a shrine, at 300 yen a pop, for a roughly 1/256 chance of getting it. Cue an hour and a half of standing there throwing money at the shrine hoping to get it.
Suikoden II has this with the upgraded forms of Fire (Rage) and Lightning (Thunder) Runes. If you wanted more than one you could freely attach (and you did, as they were useful in many ways), you had to hope for a drop from specific enemies near the endgame.
Triple-whammy of random drops in its predecessor, though—the original Suikoden. First, as in Suiko2, the upgraded elemental runes (Rage, Flowing, Thunder, Cyclone, and Mother Earth) are rare random drops from specific enemies in the endgame, and just like in Suiko2, they are useful and you want them. Secondly, most of the best armor and accessories in the game are random drops that cannot be bought in any store—it's bad enough trying to equip a single six-person party for taking out the Final Boss, God save the poor bastard who wants to outfit his entire army. Thirdly, those of the Rune Piece stat-boosters that aren't in limited quantity throughout the game are random drops from various enemies. So, if you want to do something about, say, Pesmerga's lead foot, get ready to farm like you've never farmed before—because, you see, the best part has been left for last: The odds of a monster dropping any item after combat in Suikoden are generally abysmally low, but everything described above—runes, equipment, rune pieces—has drop rates starting at around 1.5%, and going as low as a quarter of a single percentage point. Hope you didn't have anything better to do with your day.
Monsters in Shining in the Darkness, although using the confusion spell "Muddle" can also make them give you their items.
In the Etrian Odyssey series, monsters don't drop money — you get raw materials from their corpses, which you can then sell back to the local shops both for cash and to help create even better weapons, armor and other supplies. This is your primary source of income. However, monsters don't always leave things behind, and many monsters also have Conditional Drops, which require you to meet certain conditions to trigger, like defeating it in a single turn or finishing it off with a certain element/status effect. Even if you meet the conditions, they still don't always drop, unless it's a boss... and many times, getting a boss to drop their special item also blocks the regular drop.
Opoona has many monsters with rare drops attached to them. Some of these are equipment, which is expected. A few drop stat-boosting items. However, some of them drop items necessary for sidequests, and the only way to get said items is by beating up monsters until you get lucky. Having the sidequest does not, sadly, make said drops more common.
Paper Mario: TTYD has this in spades with its random badge drops. Most HP-related badges, as well as attack and defense-boosting ones, can be eventually found on an enemy, then stolen off of them, but if you want any FP-related or special-attack badges, you'll likely have to kill several hundred of a specific enemy to get them.
Averted in Ar tonelico: Melody of Elemia, where all enemies have predetermined item drops ranked from C (most common) to S (least common) based upon your "Harmonics Gauge," which is supposed to reflect how well you do in a fight. Except the way the Gauge really works, you have to draw out a non-boss fight as long as possible to get the best drops, rather than finish quickly. (And boss fights tend to take long enough that you'll max the Gauge before you whittle them down, but this is desirable for their rare item drops.)
In The Last Remnant, you mostly get random Organ Drops off the monsters you kill, though if you capture a monster alive you have the option of butchering it to get more and rarer body parts that normally would've been destroyed killing it.
The random drops in Rogue Galaxy are the most reliable (relatively speaking) way to acquire many items necessary to unlock your characters' skills.
Mario & Luigi: Dream Team has these, with each enemy having a low chance of dropping a small item and an even lower chance of dropping a nice piece of gear. It's not as bad as in some games (because giant bosses seemingly always drop any rare gear they have, and normal ones drop gear about 50% of the time), but for normal enemies it's damn near impossible to figure out what they're meant to drop in the 1 in 2 million chance they give you anything. Add a very low enemy respawn rate and well...
In Animal Crossing, virtually all shop items change from day to day based on luck. Fossil identifications and offers of foreign fruit in both versions are also based on luck.
Although not an RPG, Sim City 4 has this as "randomly develops" and "randomly awards" with city development.
Third Person Shooter
Lampshaded in Zombie Situation where after a certain wave of zombies dropped an inflatable boat Fred the Crazy-Prepared gun shop owner commented "These zombies drop the strangest things."
Turn Based Strategy
Final Fantasy Tactics A2. What you can buy is determined by what pieces of loot you bring to the Bazaar, which is determined solely by how much of a lucky bastard you are. This means that it's almost impossible to tune your team to your liking until much, much further into the game, since most classes require that you have enough abilities in others to unlock them... and abilities are granted by these same items you depend on luck for finding. So you end up having to get by with whatever you have available.
Or by looking at the guaranteed loot given for completing a mission.
Eternal Eyes has many different items available as drops, but one of the most valuable is Magical Puppets; they're the raw material for your mons, and each one you get equals a new unit. All monsters can drop them, but the chance is very low, and if you don't waste a turn opening the treasure chest it's in (no way to tell until you open it, of course), it stands a good chance of being destroyed by one of its former allies. A few chapter ends will simply give you a new puppet, so you will gain new units if you progress through the story normally, but if you want to expand your army further? Get to grindin'!
Happens occasionally in Heroes of Might and Magic, generally justified by the fact that you have to fight a big creature like a dragon or a whole group of enemy units to get it.
In the original version of Jagged Alliance 2, whether or not an enemy dropped any of their equipment when they died was entirely by chance. If you wanted to upgrade your gear past starting limitations, you had to get close with pistols and drop enemies with submachineguns and rifles and hope that they dropped them, because your only other source for weapons - the online weapons dealer Bobby Ray's - wouldn't upgrade his stock past pistols for a full month after the game started. The v.1.13 Game Mod, however, includes a starting option that causes every enemy you kill to drop all of his or her gear, though this results in your sector inventories rapidly filling up with weapons and miscellaneous gear, especially after multiple large-scale battles are fought there, but sifting through all that weaponry and equipment can yield some nice stuff. And all the crap you don't have any use for can be muled over to the Arms Dealer in San Mona and sold for an excellent price.
Wide Open Sandbox
Minecraft has mobs drop their materials and other items at a random rate when killed. Sometimes you can get a handful of the items and other times mobs drop nothing. A few mobs after an update were given rare drops where they can drop better items like weapons and raw materials.
Terraria Has the Moon charm, it only drops from Werewolves. Doesn't sound bad does it? It has a 1.67% Drop chance, to make things worse, Werewolves only spawn during a full moon, only on hard mode, have 400 HP, Very immune to knockback, and Even then, they don't spawn as often as you'll like, only chance you'll have if it's either a blood moon, or you have a battle potion. Also, Blood Moons and Battle Potions let monsters spawn near NPCs.
Non-video game examples:
In Japanese Mythology; when Susanoo defeated the Orochi; the Kusanagi was in its tail. Why is not clear; some artists have implied that perhaps some earlier; unknown hero faced the monster; stabbed it with the sword; but lost, leaving the blade to be ingrown into the beast.
Torg: "I've been putzing around for hours beating little salamanders to death with a stick in the hopes of getting a tongue out of them. And it's annoying because apparently not too many of them actually have tongues."
Random Drops can occur whenever you load a page. However, there exists a wide variety of these Random Events, which have many more effects than just giving you a rare item.
There are certain avatars that can only have a chance of being given when you preform a certain event. Some of these events can only happen once every 24 real-time hours. Coupled that these avatars are infrequent in distribution, it makes avatar-getters frustrated in collecting them all.
Sweepstakes where prizes are won by collecting a specific set of game pieces—for example, McDonald's Monopoly or Subway's Scrabble games. One of the pieces in each set is rare: the amount of those pieces are equal to the amount of prizes available for that set. The other pieces are common, so you are enticed to keep playing the game to find the rare piece. The rules usually list the odds of winning the prize, which is also the odds of a given game piece being the rare piece for that set.
In the Scrabble variation, it's easy figuring out which letter is the rare to win which prize: just look for a letter that occurs ONCE in a given prize's name and doesn't occur in any other prize names. If you live in French Canada where the contests runs in English AND French, then the SAME rare letter must fulfill both conditions in TWO languages. Fun time being the guy who has to figure how to prevent the game from being Unwinnable by Mistake while simultaneously avoiding giving out half a million cars.
Street vends, dollar stores, thrift and consignment shops - where items can range from the useless or overpriced to the rare and very valuable.
In any major city or any place with a lot of people, money and other expensive items will occasionally be dropped or lost with no way to find or contact their owners. The most commonly found, though, are small denomination change and broken items.
Thieves (and police raids of thieves or drug dealers) often run into this trope. Items stolen in a burglary or robbery or seized in a police raid can range from the utterly useless or squicky (e.g. garbage) to incredibly rare and valuable animals, art, drugs, electronics, vehicles, weapons...