Most of the unique items in the series require a guide or luck to find if you really have to find them. The world is vast, and there are thousands of containers and shelves and other places to search. Screwing up quests may also render some of them Lost Forever.
Quests in themselves also work on a similar pattern. Talk to Everyone, but be careful what you say. Many Non Player Characters tend to be quite testy, and saying one wrong thing permanently makes them angry with you, sealing off any quests they might have. In a game where you get lots of your money and experience from quests, this is a problem.
Fallout 2 featured an Easter Egg with the strategy guide phenomenon. After finishing the game's main quests, you could return to New Reno and get a Fallout 2 Strategy Guide from the old drunken priest. Upon using it, your character gains 10,000 xp, all your skills are set to 300% (this being the maximum in the game), and your display window reads "Well, it would have been nice to have this at the BEGINNING of the damn game!" You can use the item multiple times for more XP, though your skills can't improve further. If you have the item in your inventory at any point before the game ends, and attempt to save, the game will crash.
Speaking of Fallout 2, would you like to help out the NCR? Go ahead and do Tandi's mission then. What's that? You didn't tell them to Keep the Rewardthey agreed give you? Well then, goddammit you, we'll just be keeping this entire mission branch without any indication as to why.
Fallout: New Vegas: Some of the Companion Quests are nigh-impossible to complete (or even know about in the first place) unless you have an online guide handy. For many of them, you'll have to speak with specific people at very specific points at the game, and this is never mentioned to the player in any dialogue tree.
Raul's is one of the worst. You have to talk to three specific people in the wasteland. Talk to any of them before you have Raul on your party or when Raul is not on your party. The quest cannot be completed. Even worse, it's buggy as hell, meaning that even if you know who to talk to, some bug could cause the dialog with Raul to not be initiated, or for the NPC to disappear from the game entirely in the case of one of the NPCs. Raul's quest also has no quest markers or any indication of who you should talk to besides "some old guys", for extra fun.
And forget about trying to get even a moderately good ending without a strategy guide memorized and open at every quest. Not only can you not start certain quests, but if you complete some quests then it means you either can't complete others or will have no way of getting a Good Karma resolution. Bear in mind that the quests you'll already have completed may have been at about the 10-15 hour mark, and the quest you now can't complete/start/get a good ending for comes around the 40 hour mark, and nowhere in-game is there any indication of which quests invalidate others (e.g., Aba Daba Honeymoon can be rendered unfinishable by the dialog at the end of I Put a Spell on You).
You need to accumulate 5 "history" points by completing various Legion-related events just to trigger Boone's companion quest. None of the events is repeatable, neither the events nor points are mentioned in-game, and Boone must be in your party when you complete them-completing the events without him renders the points, and potentially the quest, Lost Forever. And some of the events have to be completed in conjunction with separate quests to earn the points.
Several of the trust points needed for Arcade Gannon's quest are also missable, and even once you have the required amount the quest doesn't start until you've advanced the main quest line to a certain degree. There are also "dislike" points that negate these.
Veronica's quest too. In addition to the potential for conversation triggers to be Lost Forever, sometimes even the ones you haven't yet found will fail to activate.
The check used to determine whether or not you can take a Paragon/Renegade option in a conversation is not the Paragon/Renegade gauge in your menu. There's another, hidden meter than keeps track of the total number of P/R points available versus how many you've obtained. The total includes available missions that you haven't done yet. This makes some of the checks (particularly the Jack/Miranda and Tali/Legion confrontations, where you need to pass a reputation check to keep both parties' loyaltynote if you fail the check, it's still possible to regain their loyalty if you side with the right party member and then choose a specific dialogue option when talking to the other person later, but that is a Guide Dang It within itself - and very ill-advised for the Tali/Legion conflict) almost impossible unless you've hewed 100% Paragon or 100% Renegade from the beginning of the game. Best of all, in a New Game+, the requirements to pass reputation checks are increased, but not the amount of Paragon/Renegade points in the game. Consequence: several reputation checks become literally impossible to pass without save hacking. Combined with the other "benefits" of the New Game+ compared with the Old Save Bonus, there's a reason most players recommend just starting a new file if you want to play your character again.
After you finish a certain mission a hidden countdown begins, and after you complete one more mission your entire crew gets abducted. This in itself is not so bad and certainly has a punch story-wise, however after that a second hidden countdown begins, and unless you sally forth upon the final mission almost immediately (and if you didn't complete Legion's loyalty quest during the countdown, you still have it to do), your kidnapped crew will start to die, including various characters who will otherwise reappear in the third game. What makes this particularly annoying and counter-intuitive is that at no point in the series before this was the issue of how much time the player spent between missions ever made important- indeed both games were quite fond of punishing you for charging into a story mission before you were properly prepared for it.
Unlike the prior games, side quests do not update in your log after you get them. If you miss or misunderstand what you were told to do next (like not hearing the directions properly in a noisy area), the only way to continue (assuming you don't accidentally stumble across it) is to look up the quest online.
If you don't import a saved game into the third installment, you automatically lose the potential peace between the geth and quarians due to Tali and Legion both dying by default, which can screw new players out of the best result without even knowing it.
A lot of factors for the peaceful resolution of the geth/quarian conflict are Guide Dang-Its. Didn't pass Tali's loyalty mission's Reputation check in the second game? Too bad, you get genocide - either she's not an admiral, or you got her father struck off of fleet records, losing her loyalty, and the conflict with Legion that results. Screwed that up? Same result. Got either of them killed? No prizes for guessing. Even the official strategy guide has been proven inaccurate as to which factors influence whether or not you'll achieve the best resolution. It's an act of diplomacy that makes perfect sense once you know what to do, but a Player Nudge or two wouldn't have gone amiss. Especially since the game will fake you out with a misleading dialog tree even if you pass the prerequisites... and you can still fail the Reputation check after coming this far. To summarise...
Tali must be an admiral, and Legion must be alive.
You have to have peacefully resolved their loyalty conflict - no exploiting the "gain back loyalty" mechanic for you!
You must stop the geth from shooting down civilian ships by completing the Geth Fighter Squadron mission.
And once those four must-have prerequisites are met, you must gain at least 5 (mercifully, you get three for free) peace points from any of the following...
+2 points: Tali's loyalty mission being completed successfully - this is the first freebie, as you have to do this to meet a hard requirement.
+1 point: Peacefully resolve Tali and Legion's loyalty conflict - this one is a hard requirement, so it's obviously free too.
+2 points: Resolve Legion's loyalty mission by being a Renegade and killing the heretics - integrating them with the consensus leads them to encourage dog-kicking, causing the civilian ships to panic without steady leadership.
+1/2 points: You can get one point for sacrificing Admiral Koris to save the civilians in Priority: Admiral Koris, and two for saving Koris - his leadership is the steady leadership that prevents the civilians from breaking due to heretic dog-kicking.
In order for Kelly Chambers to appear, you not only have to make sure she survived the events of the suicide mission (which meant that you immediately had to jump into the relay to save her), but you also had to have befriended her to the point that you invited her up for dinner (and her promise that she would feed your fish, one of which you had to buy on Ilium). Failure to do so means no Kelly appearance and no bonus intel from the Prejak Paddlefish (for a 10% weapon or power damage bonus). Then in order to keep her alive for the entire game, you would have to spot her in the beginning of the game, tell her to change her appearance and name and then visit her again afterwards. Not doing that means she will die during a Cerberus attack that you couldn't possibly have known about without a guide or a previous playthrough.
In order to "save" Anderson, which amounts to postponing his death by a few minutes and cause the Illusive Man to shoot himself, you have to Charm or Intimidate him during your conversations with him on Mars, Thessia and the Cerberus base. These Charm or Intimidate options are further buried within optional dialog trees and can be missed without knowing it. Passing this check, in turn, used to drastically lower the Effective Military Strength requirement for the Destroy ending, which used to mean the difference between getting the "Shepard Lives" cutscene or not. Thankfully averted with the Extended Cut patch, however.
If you're playing as Male Shepard, you can't successfully romance Kaidan unless you buy a bottle of whiskey before checking up on him in hospital for the first time. It's very easy to miss, especially as the whiskey disappears if you don't buy it straight away.
The only way to save Miranda from getting killed by Kai Leng is to read an email on him before messaging her, otherwise Shepard won't know to warn her.
A number of side quests will disappear without warning once you get past certain arbitrary moments in the game, particularly most Citadel fetch quests after the Cerberus take-over, replaced by a whole bunch of new ones. The easy way to avoid this to not do any "Priority" missions until dead last.
When Samantha Traynor gives Shepard a warning about a Cerberus attack on Grissom Academy, it's best to do that mission some time before Priority: Citadel II. Why before then? Because if you don't do the Grissom Academy mission soon enough, Cerberus captures Jack and brainwashes her into a Phantom, and you have to kill Jack during your assault on the Cerberus base later. There is no warning given in advance that you have a time limit.
In the same vein as the Grissom Academy mission above, you should do the Tuchanka bomb mission before Priority: Citadel II, because if you don't, the bomb explodes and takes out most of Kelphic Valley, taking some War Assets with it. This time you have some warning, since it's just common sense that you can't leave a bomb lying around, but you still aren't told exactly when the bomb will go off.
The "Threads of the Webspinner" side-quest requires you to find multiple (read: 26) individual pieces of Sanguine equipment. The quest give will only tell you about a few of the pieces, while the rest are on seemingly random NPCs scattered throughout Vvardenfell. (Some are even possessed by non-hostile NPCs in towns, virtually guaranteeing that you'll get a bounty for killing the holder.) Even worse, if you don't find out about the quest before you start uncovering some of the items, you may have accidentally left them behind or sold them. (While each has a rare enchantment, they aren't very powerful and are usually outclassed by other equipment you have at that point.)
The expansions add the previously-unique effects of these items as purchasable spells, making this quest even more pointless.
One of the early missions of the main quest has you searching a large Dwemer ruin for a specific item (the Dwemer puzzle box.) While the item is located in a relatively easily-reached portion of the dungeon with few guards, it's located in a small nook off the obvious path in such a way that few people will notice. Even then, the item itself is small and the same color as the shelf it's sitting on in a low-light area. The official forums had a several hundred page stickied thread dedicated to helping people find it.
To make matters worse, if you go to the dungeon where the Dwemer Puzzle Box is located before you receive the quest to fetch it, the puzzle box is there... but cannot be picked up. This could lead some players to believe that it's something that simply can't be interacted with - interesting-looking scenery, effectively.
Finding the Cavern of the Incarnate as part of the main quest mission "Path of the Incarnate" is difficult to find even with a guide. The in-game directions are incredibly vague and in riddle form. Even with a guide handy, the cavern is located in a maze of hills, rocks, and Cliff Racer ambushes. And when you do find it, you can only enter it during two two-hour periods of dawn and dusk in the game.
Acquiring Eltonbrand, to the point where acquiring it without a guide would be nothing short of a miracle. To summarize, you first have to start the already obscure quest to acquire Goldbrand. Only one character in the game even gives you directions to the shrine you need to visit, and he is a.) not very trustworthy and b.) gives you inaccurate directions. Then you get even more vague directions from the Daedric prince in question to find a sculptor, who then asks you for a large sum of money and a unique book. Once you do all of that, you then have to wait the two in-game weeks for the shrine to be built in order to receive your reward. Then, to upgrade Goldbrand into Eltonbrand, you have to first become a vampire (which can be difficult enough to pull off, or near impossible if you've advanced far enough in the main quest to receive disease immunity.) Then, you have to complete one obscure vampires-only quest and have a specific amount of gold in your inventory (11,171) when you report back to the quest giver.
The quest "A Venerable Vintage" requires locating six (infinitely respawning) bottles of Shadowbanish Wine and is often added to players' quest logs early on in the game due to the fact that the quest is received in the first settlement players are likely to encounter once first venturing out from the Imperial City. After that, with this being one of the quests acquired so early in the game, that quest is pinned to the top of your quest log ... for the entire game. Seriously, this is one of the last quests players ever complete. Whereas most quests provide some exact indication of where to go due to the vastness of the game world, the only hint Nerussa provides is that it is found in abandoned forts located about Cyrodil. There are easily 40 forts in Cyrodil (50+ with expansions), and only eight of them (or 10 with expansions) have the vintage. A typical fort can take a good 20-30 minutes to slog through the darkness, the worst ones literally being mazes in spite of the auto-mapping feature, with monsters all the while ambushing you from the darkness. The reward for this quest is a somewhat respectable 1000 gold. If you are the type of player who detests exploring forts and caves, either consult a guide or don't even attempt this quest.
Seeking Your Roots is another candidate for the Permanent Active Quest Club and is just as bad. You must find 40 Nirnroots to complete it, which are very rare plants that do not regrow (there are about 300 in the entire game, though) and worst of all, are scattered all over the landscape with no obvious pointer as where to find them note You are however told that they are likely to grow near water. Likely. Your reward is a series of fortifying potions that become decreasingly lousy as you deliver more samples of the stuff, 10 at a time. By the time you get to the stronger potions, and assuming you had any interest in Alchemy (why else would you be running around the field looking for the things anyway?), you can craft stronger potions with common ingredients, and would probably be more inclined to use the Nirnroots to craft strong poisons.
Also in Oblivionhorses can see you steal and will "report" your theft to NPCs, including the theft of horses. So in effect, the horse that you steal will "report" being stolen if it sees you mounting it. To avoid this, players need to sneak up on a horse and mount it from behind. And if you're stealing a horse from a group of horses, you need to either separate the horse you plan to steal so that the rest of the group doesn't see it, or push the other horses to rotate them into looking away.
Ochendor, the renegade cult leader Daedra Prince Peryite tasks you to track down (in the depths of a Dwemer ruin) and kill, is immune to magic. As in, destruction spells do no damage. Now, sometimes enemy NPCs can be invulnerable (usually for cutscenes, dialogues, etc.) and sometimes the game can glitch and not remove the invulnerability, usually when you accidentally interrupt a script. Now imagine you're a magic-focused character, you approach the guy, the fight starts, and you can't damage him. It'll probably take a few reloads to "fix the bug" before trying to harm him in any other way. No, there's no mention of how or why this guy is immune to magic (practically no one else in the game is, even much more serious bosses) and he's not carrying any items that gives the ability either. He's just immune to magic for no reason at all.
A Return To Your Roots, because apparently we didn't have enough of the damned things. This time around they are red. Fortunately, they hiss when you are near, they regrow (slowly), only 30 are required, there's a huge stash hidden that's almost enough to fill the quota, and the reward is far superior: the ability to craft 2 potions with the same ingredients 25% of the time.
And another collection quest... it almost seems like a Running Gag. Scattered through the world are 24 'unusual gems'. If you show them to an appraiser, he or she tasks you to find all of them. Now, most collection quests give map markers to show in which location the things you're supposed to get are. This quest of course doesn't. And the gems can be anywhere, from ordinary dungeons and forts to the private collections of jarls and court mages. One was even in a location that was only reachable during one particular part of the main questline, but it was moved in a patch. However all of these locations are connected to at least one other non-radiant quest, meaning the chances you'll stumble upon one are increased ,than if they were put in a location that's not connected to any quests, though this still makes things very tedious. Luckily, a few mods exist that make life easier, either by adding quest markers or by just putting all gems together in an easily reachable location. As with A Return to Your Roots, at least the reward is absurdly good, in this case a permanent ability that massively increases your odds of finding precious gems*
from about a 10-25% chance of one in certain well-guarded chests, to a guaranteed 2-4 gems in practically every chest within a dungeon
, more or less eliminating your money problems from that point forward.
From the Thieves Guild comes the Larceny Targets quest, which has you nab something of value from various dungeons and estates. Good news is all of these places are visited during the main quest, so at least you won't have to run across Skyrim. Bad news is, good luck knowing this without checking at least one guide or having done this quest before. Even if you know an item is within a specific place, it's fairly well hidden (except for 2 or 3, which are placed in the open for the express purpose of letting you know they exist). The Falmer Eyes are the most prominent). The difficulty also ranges from "you-got-to-be-blind-not-to-see" to Guide Dang It, as some are hidden as pieces of scenery, in heavily guarded areas, behind a series of annoying traps, or just hidden in places you didn't even know existed. Granted, being in the Thieves guild you're expected to nab everything that isn't nailed down, so it's at least a bit better than most examples.
On the first level of Undermountain in the Hordes of the Underdark expansion for Neverwinter Nights, there's a secret door that can only be discovered when a specific non-hostile rat is within ten feet of the door. There's no indication of this in the game, save that the door will sometimes refuse to appear regardless of your character's Search skill rank. This is hardly game breaking, and you can open the module in the game's level editor to figure out what's going on, but it still makes very little sense.
The Gay Option in most RPGs is usually so well-hidden from Moral Guardians even the gamer might not figure it out. Take Jade Empire, for example... the only way to get Sky to date a male PC is by being Open Palm and shutting down the romances with both Silk Fox and Dawn Star. Because 'nice' conversation options get you higher good points, it's pretty close to impossible to figure out how to let the girls down gently while still being 'good' enough to catch the fella's interest.
Soundly averted by Zevran in Dragon Age: Origins, however. Short of simply not talking to him at all, it's near impossible to prevent him from hitting on you. Leliana is more "hidden," but she's almost as difficult for males to get as well.
Or rather, she's glitched without the right patches (which are a Guide Dang It of their own, since they are never automatically checked for outside of Steam), so that you can't initiate her romance if she likes you too much. Also, for those who talk to her between every gift, starting her romance by accident is fairly easy as well, making avoiding it a Guide Dang It of its own.
The Amiga/Atari classic Captive was a particularly heavy offender in this category. The game manual neglected to inform you on such frivolous little details as:
If you want your droids to be able to learn (gain XP), you need to put the "droid chip" into the "brain" slot in each droid's inventory.
Oh, and did we forget to tell you that in order to locate your next objective, you need to enter the correct password into a giant computer to get a Planet Probe that will reveal the next base on the star map? The password is on a clipboard carried by a scientist in white lab coat. No planet probe? Good luck trying to find the next base.
You'll really want to get everything else in the base out of the way before blowing up the generators, as after that things get all explode-y in a hurry. You did write down the four-button combination for the outer door, didn't you? Oh, and the optics device that leads you back to the exit can be quite handy, especially later in the game.
At the Space Station, however, you do not want to blow up the generators as that's where you are being held. Succeed in blowing up the station and you've managed to commit a needlessly elaborate suicide. Congratulations.
You need to recharge your droids by putting your "finger" (the mouse pointer) into an electric outlet (gray square at the bottom of a wall with three black dots) and then sticking the electric charge onto the droid's chest. Especially annoying since touching anything other than a droid chest or a battery with the electrified finger causes said item to explode. Accidentally clicked an arm instead of a chest? Hope you have a recent savegame handy.
Dice can be used to "decode" the four-button code locks, except the ones on the outer doors of the bases.
Much like the "Rumplestiltskin if the alphabet is backwards" example near the start of this page, browser-based MMORPG Travians includes a spell of protection where you have to say the first letter in each word of the spell. The only clue to this is the word "SHORTLY" as in "Enter the house, and say SHORTLY: Great Mother! Protect this house!" etc. etc. As the letters don't even form any manner of word themselves, nobody could get that without looking at the Quest Guide.
In Drakensang it's straightforward at least. A woman asks you if you know the password (44SC2K). If you do, she'll give you a magical item.
This was actually the key to a promotional item, the key was sent to people who preordered (IIRC). "Nice" idea, but badly executed.
The item itself was a reference to the old DSA games of the nineties. And the Gold Edition included it without the need for a code.
Wizardry IV is a massive offender of Guide Dang It, with devious dungeon layouts, random hidden doors and one-way walls, and puzzles which required pop culture knowledge to know which item to use, let alone where to use it. The very first room is one of the most glaring examples: there's seemingly no way out of the room you start in. There's a hidden door, which you need a light spell to find and enter. But Werdna can't use light spells! So you summon some Priests. But you can't command your monsters outside of battle! So you have to get into a random battle and hope that one of the Priests randomly casts a light spell so you can use the hidden door once the battle is finished.
In Wizardry VII, some of the puzzles are nigh-incomprehensible without the guide. Map pieces in the game give you clues on occasion, but even with all of them you will do lots of aimless wandering.
One of the more versatile (and cool-looking) spells in Lands of Lore: The Throne of Chaos is only attainable in the abandoned city of Yvel about two-thirds of the way through the game. Most of the doors in this city are boarded up, but there is one boarded-up door that can be opened, and the scroll for the spell is waiting inside. By the way, all you have to do to open this door is click on it several times with the mouse cursor...but the door looks exactly like every single other boarded-up door in the city, and nowhere else in the game are you ever required to click on random background scenery for any reason.
The game is peppered with other instances of this trope. Example One: using the Green Skull is the best (and possibly only) way to kill the Lahrkon guarding the Urbish Mines, but you might not figure this out until you'd tried everything else. Example Two: the fact that the Emerald Blade is the best (and possibly only) weapon to use against Wraiths is only mentioned once, in an easily-missed book in the only library in the game, which is located on the very first map, which is inaccessible by the time you're fighting Wraiths, which are easily capable of wiping out your entire party in a single blow. It's also possible to miss both Green Skulls and both Emerald Blades.
Worse, it's possible to screw up due to the Barrier placements and have your only other available weapon against the Wraiths Lost Forever. Bye bye plot development.
When Star Wars: Galaxies was first released, Jedi characters had to be unlocked through specific in-game actions.
Consider that the original version rewarded either balls-out grinding (to master EVERY skill set) or canny deduction and numerology (to figure out which ONE skill set to master). Making it stupid would certainly anger just about everybody.
Gamers tend to hate when you render all their "accomplishments" trivial.
Might and Magic II requires you to go into a dungeon to retrieve King Kalohn's Element Orb. However, as long as the Orb is in your inventory, a magical barrier prevents you from leaving the area which, by the way, is also an anti-magic area preventing the use of teleportation spells. What you are supposed to do is to give the Orb to a hireling and dismiss him from the party. The hireling will then somehow find his way back to the last visited inn with the Orb still in his inventory. That's right-abusing game mechanics is the intended solution to this puzzle.
Baldur's Gate 2: Shadows of Amn: During a paladin stronghold quest, you are required to guard a young lady (actually a rude, spoiled brat) from assassins until a relative comes to pick her up. When the relative finally shows up, the only way to ascertain he's not an impostor and thus finish the quest succesfully is to cast 'detect evil' in his presence. There is no hint given that you must do this, and the spell is never used anywhere else in the entire Baldur's Gate saga, such that some players might have even forgotten they had it at this point.
Baldur's Gate 2: The Throne of Bhaal for the best piece of armor (the Big Metal Unit) you must have play the first game of the series and steal the pants of a random nobleman, play the second part in which you save somebody from certain death, do some detective work to find the wrongdoers, but instead of rescuing their hostage you have to collect the ransom for her and finally in The Throne of Bhaal you must hire 3 of the weakest characters in the world to face an unknown threat. Only if you have done all that and kept the pairs of pants that have absolutely no use whatsoever, yet another guy (who needs to be found, too) can forge them into one.
Keep in mind that your entire inventory is wiped right at the start of 2. The only to prevent this from happening is to quickly go into your inventory seconds after the game starts before you hear your character gasp (which is when the inventory wipe happens) and dump everything on the floor.
Though if you don't do that, the Golden Pantaloons will be spawned into the locked and trapped painting next to the chest and table full of armor and weapons near the start of the game, but only if you imported a character with them.
The labyrinth at Spellhold killed a lot of people through this and Fake Difficulty, by placing an undetectable, unremovable smashing hallway trap in an entirely unremarkable corridor. Located right next to an enemy that was no danger at all by this point save for its ability to cast Confusion, which causes players to run around at random. Of course, if you know it's there about five different ways of getting around the problem present themselves.
Diablo II had this problem to an extreme degree with its game mechanics. To name a couple examples among many: the attack speed shown in game was/is wrong, the interaction on poison damage and time was not explained. Both of these mechanics had to be determined outside the game by testing, as did the other Guide Dang It mechanics.
Different weapon types had bonuses against different enemy types; only one of these (Bludgeoning types against the undead) was actually mentioned in game.
The entire skill/stat placement system was one big Guide Dang It, as it was very easy to nerf a character by distributing points incorrectly. For most of the game's lifespan, the only way to be strong enough for higher difficulties was to save skill points until you had unlocked high-level skills, as low-level skills were too weak even with heavy investment, and allocate stat points based on what you would need for Hell mode. Fortunately, this was fixed in a later patch, with low-level skills providing damage boosts to higher-level ones and the ability to reset stat/skill distributions.
Blizzard couldn't be bothered to list all the interactions between skills:
When active, Concentration gives a damage boost to Blessed Hammer at 50% efficiency. It's never mentioned anywhere, and since these are the only aura to boost magic skills and the only magic skill to get the boost, there's no reason to expect it.
Energy Shield's synergy with Telekinesis is mentioned on the skill tree, but never explained: investing skill points in Telekinesis decreases the amount of mana lost per damage prevented.
Diablo III continues its predecessor's proud tradition of lying character screens: Battle.net and the in-game character screen both give inaccurate damage/second information, and don't necessarily agree with each other.
Attacks that can run continuously, such as Arcane Torrent, never specify how long it takes for them to do the listed damage or consume the stated amount of mana or equivalent. Despite the skills running continuously, the mana consumed/second is equal to the listed cost times the number of attacks per second, even though the latter has no bearing on how these skills work or deal damage.
Before patch 1.0.8, items on the Auction House only listed changes to base stats or damage, so you needed a calculator or 3rd-party site to figure out whether an item would be an improvement over your current equipment. Damage/second comparisons were added in 1.0.8, but even now, there's no way to account for skill-specific damage boosts and the impact on damage reduction/dodge chance still has to be done by hand.
Proc coefficients are one of the game's worst offenders. They are less than intuitive and integral to many builds, but are mentioned nowhere in the game or Battle.net's official guide.
If a weapon has a chance of causing a secondary effect, the listed chance is misleading: Each skill has a hidden proc coefficient, and the actual probability of the secondary effect occurring when you use that skill is (proc coefficient) * (base chance).
A handful of runes and passive skills have "a chance" to trigger and provide some beneficial effect when you land a critical hit. Same deal as above, except even the base chance isn't even given.
Proc coefficients can vary even within a skill based on the rune used, and some skills even have a coefficient of zero.
Life on Hit has a different proc coefficient than all other effects, and the third hit of the Monk's primary skills has a different proc coefficient from the first two.
World of Warcraft: Mankrik's Wife. That says it all. On the Alliance side, the quest "Fiora Longears" was easy: travel to Theramore, talk to the eponymous NPC... until she was arbitrarily moved to Auberdine and the developers forgot to update the quest description, leaving the players clueless for months until it was finally fixed.
The Horde's Call of Fire quest deserves a special mention in this case. Midway through the quest, you are required to fetch two items. One of these is a reagent pouch, which the quest-giver says you can find on Burning Blade cultists in a cave northeast of Razor Hill. Gee, that sounds like that cave you went to during that Skull Rock quest, right?...Er, not quite. Turns out that he was talking about a different cave — but you probably won't figure that out until you've spent two hours wondering why none of these damn cultists in Skull Rock are dropping that pouch you need.
It could be argued that the very gameplay itself is an example of this trope, at least in endgame. Yes, you can solo your way to level 80 without checking out any external sites etc., but let's take a look at some of the incredibly fundamental information for running instances that the game never informs you of: At 540 defence(at 80th level), a tank becomes immune to critical hits. When someone parries an attack, their next attack is sped up. When you're standing behind someone, they can't parry you. Long story short, the tank takes a lot less damage if the damage dealers stand behind the monsters. Now just consider how many tanks died because of people not knowing those three facts.
Blizzard is currently making a valiant effort to fix this, at least for the most part. The Cataclysm expansion has changed many of the talents and skills to very basic and obvious descriptions. "This spell deals damage, use it a lot." ... "This talent makes you take less damage. That's your job, meatshield." They've also added no-duh descriptions to the early-game talent selections. "This is the tank skillset. You will be the meatshield. Are you sure you want to chose this path?" or "This spell increases your maximum health. You should always have this active on yourself and your party members." Certainly, the end-game raid bosses will still require much external research and planning, but at least people should have basic info without any research.
Talents receive similar treatment; each talent specialization (the "school" of talents your character chooses to primarily study) automatically includes up to four abilities specific to that class and specialization; in prior expansions, these were hypothetically optional, but in practical terms were "must haves", so the developers decided to just give them to you. Other obvious talents are given descriptions that essentially inform people "If you don't take this talent, you are a terrible player".
With Mists of Pandaria, the talent system has been simplified to the point at which there are six tiers in which you can choose one of three talents. On the other hand, not only are some talents considered "ideal" for certain roles, but players are often expected to change the talents on a situational basis.
Cataclysm also seeks to further simplify weapons and armor (much to the chagrin of "hardcore players") by removing many of the different stats. For example, a physical damage dealer (rogue, warrior, etc) in earlier expansions had to balance Agility, Strength, Attack power, Hit Rating, Critical Strike Rating, Expertise and Armor Penetration... along with enough Stamina to survive a few splash damage attacks. That's seven different stats to look at, and a good number of them were rather redundant anyways. Cataclysm specifically calls out a primary stat for each class: Agility for Rogues and Shaman, Strength for Warriors, Death Knights and Paladins, or Intellect for spell casters. A few stats, largely perceived as redundant and non-intuitive but important nevertheless (such as expertise, which reduced the chance of enemies dodging and parrying your attacks) remain, and the addition of mastery (a stat which does very specific things based on your character's specialization) complicates matters further. Still, it's enough of an improvement that one can safely assume a class-appropriate level 359 item is better than a level 346 item of the same type.
In addition, the new Reforging option that allows you to change part of the stats allocated to your equipment more or less mandates that every class and specialization knows their stat priority and allocates as much stat points as possible from suboptimal to optimal secondary stats. Said priority is only available on forums and in external player guides and is a result of empirical research rather then something the developers actually enforce. Thus stat 'weights' often change when classes undergo overhauls.
Nor does the game specify in any way what enchants and socket gems are optimal for a given specialization at a given level. Is +500 Nature damage better than occasionally getting +1200 Intellect? To find out, you'll either need to spend a ton of money on enchants, or look it up on a third-party site. On some trinkets or enchantments with a proc, there is an "internal cooldown" that prevents the proc from re-occurring within a certain period. When comparing a trinket that randomly procs with one that has a cooldown, you must not only compare the relative benefits of each one in terms of statistics, but how often the latter will proc, which you will not be able to find from in-game information.
In short, the gear optimization metagame has grown so complicated that automated spreadsheets have been developed by advanced players for specific classes that automatically parse character data and decide for you which way should your gear be optimized.
To say nothing of stat caps. While most stats improvement follow the general rule of "more is better", some stats will suffer critical diminishing returns after a certain amount is reached (or Soft Cap) while others will cease giving any benefit whatsoever past a certain point (Hard Caps). While it is possible to discover some of these on your own if you ferret deep enough in your character stats ("Hey, why am I putting more hit rating on my mage if I already have 0 percent chance of missing?"), some are so obscure (such as the mage 25% haste soft cap) that they are definitely trope worthy and a sign that you need to do more online research for your optimal build.
Haste is an especially non-intuitive statistics, especially since for classes that use damage or healing over time spells, getting haste to a certain threshhold, you get extra ticks for each spell, since haste determines the time between ticks (for example, a HOT with a duration of 4 seconds has four ticks if it ticks every seconds, but gets a fifth tick if you increase your haste to the point at which it can tick every .8 seconds). This involves gearing to fairly specific break points; you won't get the extra tick if you're a little short, you'll likely benefit very little from extra points unless there is a nearby breakpoint, and it's hard to determine those breakpoints without a chart, especially since haste buffs come into play.
All of Blizzard's releases this millennium can be extremely frustrating without a guide, hence the reason they've started giving them out with the Battle Chest releases of Warcraft III and Starcraft.
Blackrock Depths. This is just a pair of Guide Dang Its, but they're critical: the dungeon cannot be completed unless you get the Shadowforge Key and unlock the Shadowforge Lock with it. However, you can run half the dungeon without it, only to find yourself in a dead-end without explanation. There is never an indication you must have the key, nor where to get it, nor does anything tell you that you have to take a quest from a ghost outside the dungeon whom you can't even see unless you're dead and that you need to not kill a unique dwarf you're going to find before you have the quest, or a completely required item won't drop and the dungeon has to be reset. Later on you hit up a tavern with a locked back door, and indications you need a key to get through it, but there's no way to get it. How do you get through? Four ways: pickpocket the tavern owner and risk death when he finds out and everyone there attacks, kill someone to summon a guard patrol (which never happens anywhere else), do a quest for an NPC there that requires you leave the dungeon and fly around the world gathering bits, or give an otherwise normal looking dwarf several beers, at which point he'll smash the door down for no reason other than he wants to be drunker.
Actually he smashes a keg to get more booze, and the security golem (Phalanx) smashes through the door to stop him.
The endgame content is pretty much entirely this, as it is utterly reliant on knowing in advance things that are never mentioned in the game. Practically every raid boss will slaughter a group where people don't already know what it's going to do. As such, pretty much any raid leader will expect players to have done some external research into the boss encounters, and to have add-on software installed that calls out the boss's abilities as he uses them. High-end guilds often participate in this content before such third-party resources are available, and as such can spend the better part of an evening on a single fight, getting killed repeatedly until they learn all of the boss's tricks.
This was particularly bad in before, as pretty much everything before the endgame content was just "attack, fight, kill," then the endgame content began throwing this stuff at you. Cataclysm made this a bit better by having a few bosses in earlier dungeons that are effectively previews of this type of endgame boss. Some trash mobs also serve as a preview of their respective boss' mechanics; before raids can face Yor'Sahj the Unsleeping in Dragon Soul, they must contend with six different types of slimes, in groups of three, each of which uses a single ability similar to one that Yor'Sahj can use.
There's a quest in Felwood based on the Arthas vs Illidan fight a while back. When the quest-giver summons an image of Illidan monologuing, you expect to just kick back and watch some fireworks. However, once the fight ends, you'll notice that you never saw Arthas the entire time, and when Illidan lost, you were marked as having failed the quest. You need to jump in and fight Arthas yourself. Now going back to what was just said, you never saw Arthas, so you can't target him, meaning that Illidan can't win and you can't succeed. How to get around this is to go to where Illidan is and look where Arthas will appear, which first off, the quest never mentions having to do, and second, you don't know where Arthas will appear since you can't see him. If When you fail the quest enough times, it will eventually give you a different quest.
There's a new quest in Loch Modan, where you find a Dark Iron spy's list of drop places for parcels, which you can go around collecting and giving to a Dwarf NPC for experience. The third note is listed as being in the back of a cave on the southern side of a hill that's just south of Thelsamar. Logically, you look at Grizzlepaw Ridge, which fits the description perfectly. Except, there are two caves on that hill. One is a large, Trogg-filled cave on the southern face. The other is on the eastern side, but still sort of fits the description, since it mentions the path to the cave, which does begin on the southern side, and that it's at the top of the hill, and the larger, southern cave is at the bottom. After thoroughly investigating both of these caves, you'll notice that the item isn't anywhere in either of these caves. You'll later happen upon another cave, not to the south, but much more to the southeast of Thelsamar. There's also the fact that there are no quests leading you here, meaning that most players have no reason to go here.
Speaking of covering tracks, there's a handful of ways to do it, with varying degrees of success. The problem comes in that when you do one of the major server hacks (that spawns a "Find Out Who Hacked Us" mission that, in older versions, you could accept and submit 127.0.0.1 for), the game slowly checks the logs on each server in the chain until one of two things happen. The first case (which you want) is that the trail is completely lost by a properly-done log wipe. The second case is that they manage to trace it all the way back to you because you forgot that when you disconnect, you leave a log message saying you disconnected (which, if not paired with a connection log message, does not stop a slow trace). And there's still a chance that the game might bug out and get you anyways.
The beginning tutorials of Gaia Online MMORPG zOMG! have been altered, edited, debugged, taken apart and reassembled, and generally changed so much that they no longer tell you much of how to play the game. Things like Ghi, suppressing your level to farm in lower-level areas, ring CL swap, and salvaging your spare rings for orbs all have to be explained in the forums.
There were a few moments even before the tutorials were removed. The Tiny Terrors in the Old Aqueduct and the Anchor Bugs on the Buccaneer Boardwalk do not count towards kill count badges for those respective enemies (though the Bugs still drop loot, and both can drop charge orbs; this makes farming the quickly-respawning Aqueduct Terrors quite rewarding). The goal of the Gauntlet is to run away.
Dragon Age: Origins. Try getting Sten's approval up without being told how to do so. Gifts especially. Sure, you can probably guess some of the gifts by the character (Andastre Relic...oh, Leliana from the Chantry would like this! A scroll...maybe I should give this to Wynne. Booze? DEFINITELY give that to Oghren...) but there are some other ones that aren't as obvious, other than Trial and Error. (Hmm...Oghren doesn't seem to like Wine at all...who would...oh, Wynne? Gold and Silver bars...maybe Ogh...oh no he doesn't like that...neither does Alistair. hmm who do-Zevran?!)
Not so difficult actually. Most of the unintuitive gifts become at least reasonable once you have enough rep with the person and have explored all their dialog. "Who the heck is going to want a cat? Maybe Liliana..." *Reps up with Alistair and does some dialog* "Oh! Alistair had a pet cat that he lost, there we go.." Similarly, Sten becomes much easier to gain approval with once you learn a little about the kind of person he is.
Also from Dragon Age: Origins, The Fade is just convoluted and unintuitive. You are either spending an hour or so with a guide (Because it takes awhile to get through), or you spend several hours backtracking trying to find all four forms... less so if you took notes, but that's still annoying. It's to the point where one of the most popular mods for the game is the ability to skip this level entirely.
The only Guide Dang It aspect is where all the forms are. The golem doors, mouse holes, and spirit doors are all visibly shown on the map. The fire walls are not, but it isn't like you are going to miss them. You do need to backtrack a lot and the most efficient way through the area with minimal backtracking is not obvious. However, you do not need a guide to complete this area. The level design is extremely simple, you just need to find all the forms to get through the clearly marked door to get to the clearly marked boss room.
The climax of Dragon Age: Origins – Awakening involves a choice between saving Vigil's Keep and saving Amaranthine, in which if you do not save Vigil's Keep, it falls and all your companions left there are killed. That is, unless you completed a series of seemingly not-too-important side quests and also agreed to pay a ridiculous amount of money very early in the game. It would not be so much of a Guide Dang It if the player were not led by the original game to consider the amount of money demanded ridiculous; however, since it's about 20 times easier to earn money in Awakening than in Origins, not only is it unlikely a player will have enough money to pay for everything at that stage, it is equally unlikely they'll be willing to part with that much gold.
Alistair's romance plot is relatively predictable and easy to navigate. Except for one seemingly-innocuous conversation option in the first half of the game right after meeting his sister which changes his entire personality, making him more open to the idea of being king, and also to the idea of keeping a female non-human-noble Warden on as a mistress after becoming king. It is also the only way to keep him from dying or becoming a wandering drunkard if you choose not to kill Loghain. If the player does not take this option, it never becomes available again, and nothing you say makes any difference to the eventual outcome of an Alistair romance. The only way a romance with Alistair can work out if you don't change his personality is if you're a female Human Noble and Alistair either remains in the Grey Wardens and lets Anora become ruler or Alistair becomes king and you pass a Persuade check so he'll still keep you around.
Leliana's romance has a similar moment of choosing, a bit after you either kill Marjolaine or let her go. If you change Leliana's personality, she'll be open to the idea of a threesome with Isabella, will (sometimes) not lose approval if you commit immoral acts, and a Persuade check opens up that, if you pass it, prevents Leliana from leaving the party if you do what Kolgrim wants and defile Andraste's sacred ashes with dragon blood.
Ancient Domains of Mystery is full of these. Merely surviving to the early mid-game is possible with some trial and error to learn how to dodge the anvils the RNG will throw at you. Actually completing the game without spoilers is non-trivial, and Ultra Endings are practically impossible to reach by mere trial and error. (Though clearly not actually impossible since somebody first discovered them, either by Save Scumming or investing more time than any mortal has.)
The most egregious guide dang factors are that 1) you should keep track of the first monster you ever kill and 2) you may want to avoid killing cats (I wish I were joking).
It was reverse-engineered. The game's author was not pleased.
An ultra ending will require strategically switching alignments at least twice, gathering several items that are usually easier to wish for than to find naturally (a Wish being one of the rarest things in the game) and completing multiple sidequests whose very existence is well-hidden in a certain order.
There is a quest as part of the main plot where you encounter Khelavaster, the sage that is mentioned in the introduction. It isn't mentioned anywhere except in oblique hints that he is the key to obtaining the artifact that unlocks an Ultra ending. Yet he blocks the down staircase, preventing progress until you talk to him. When you do, he automatically dies, which lets you go on but also removes the possibility of him summoning the Trident at the end of the game. What you actually have to do is find an Amulet of Life Saving, which are incredibly rare (some people have spent several real-time days trying), and give him one before you speak to him. (Just don't accidentally talk to him when you have one in your hands.)
Kingdom of Loathing, despite falling under this trope on numerous occasions (like most of the Holy MacGuffin quest, just for starters), actually averts it with the special monsters in the final dungeon that can only be defeated with a specific item. The game gives you a hint after losing to them for the first time, which grows increasingly more specific until the fifth or sixth one tells you exactly what you need and where to find it.
Blessed/Uncursed/Cursed status detection. Cursed items in NetHack are Bad News. If you don't know how to detect them, you'll waste lots of scrolls uncursing them, or walk around with cursed armor and attract hits, basically meaning you need to play as a priest or die. What the game doesn't tell you is that you can detect curses for free at any altar in the game, even of a god that doesn't like you, just by dropping the item on one. This is made more confusing by the fact that the game does tell you how to offer items to gods at altars, and to do that, you don't drop the items, you use a special Offer command. So you won't discover this use of altars in the course of their normal use.
And if you can't find an altar, drop an unknown item near your pet and wait a while. When it walks over the item, it may "move only reluctantly," meaning the item is cursed. Nope, the game doesn't tell you that either.
Removing cursed items. Some of them make sense (reading a scroll of destroy armor, letting a nymph steal it), while others are more out there (dipping a cursed item in a fountain has a 2/15 chance of breaking the curse, cast stone to flesh and eat it).
Excalibur. This is one of the easiest artifact weapons to get. All you have to do is choose a lawful character, advance to at least level 5, and dip an ordinary long sword into a fountain. But there are no hints to the combination, and no messages saying why you have failed or why you're successful. Further, it only works 1/6 of the time, so even if you stumble on the correct combination you could rust multiple swords into uselessness trying it.
Nethack is a game of exploration. Reading the "guide" spoils the point of the game. That said, there are clues to Excalibur-dipping. Rumors (which pop up in fortune cookies, from the oracle, etc.) has this entry: "They say that the lady of the lake now lives in a fountain somewhere."
Sting is another example. There's a function of the game that lets you assign a name to an object; by all appearances, its only use is to help you tell unidentified items apart. But if you pick up any elven dagger and name it Sting, it will suddenly gain the powers of Bilbo's sword from The Hobbit. (Faintly justified since Bilbo did, in fact, name his own weapon, but it had magic powers before he started calling it Sting.) There's also Orcrist, an artifact elven broadsword gained the same way.
The game gives you very few Scrolls of Identify, so you have to experiment with your inventory to find out what most items are. There are a lot of ways you can do this without using an item outright, which is fortunate because using the wrong item at the wrong time gets you dead. Some of these are intuitive: if you throw a potion at a wall next to you, you'll "breathe the fumes" and get a tiny dose of the potion's effects. But some are bizarre: if you drop a ring into a sink (in a game where the drop command normally puts the item on the floor), it will have a magical effect on the sink, usually a pun on the ring's normal effect. If you really wanted to play without a guide, you'd have to test rings the hard way by wearing them, then drop them in sinks to see the magical effect (because there's no way in hell you'll guess what the effects mean on your own), then record the results so that next game you can identify that particular ring.
It has been long debated as to whether NetHack is possible to beat in its current form without recourse to spoilers or sourcediving. Arguments end up focusing on what exactly constitutes a spoiler and whether price-based identification of items is actually cheating or not, but the general suspicion is: yes, it is theoretically possible, but it's seriously hard work — and proving such an achievement is even harder.
Slash Em Extended has a set of weapons capable of breaking down iron bars. Basically, it's a list of random weapons including steel whips, torpedoes and electric swords, some of which nobody would even consider of being able to break bars. The only way to find out about them is to try applying every weapon at a square containing iron bars and hoping it does something.
Runescape has clue scrolls, a sort of elaborate treasure hunt in which you solve a series of puzzles and challenges leading to a cache of treasure. Most of these offer enough in-game hints that a diligent player can solve them without a guide. However, there are some exceptions:
One clue tells you to use the panic emote in the "heart" of the Haunted Woods, which is an undefined area with no conspicuous landmarks to distinguish it from the rest of the Haunted Woods. And the area is crawling with goddamned vampyres and leeches, and you can't use emotes in combat, so trial and error won't get you very far.
Another tells you to look for a "throat mage." Most clues ask you to solve puzzles and riddles, so one can be forgiven for not expecting the solution to lie in a Stealth Pun. You're supposed to look in the Necromancer's Tower. Get it? Neck-romancer? HA HA HA! To make matters worse, the Necromancer's Tower is pretty much a piece of scenery that nobody ever goes to for any reason.
Speaking of clue scrolls, there is a quest in the desert series called Do No Evil, where you attempt to introduce Planet of the Apes type monkeys into the desert ecosystem. One part of this quest is to use the equivalent of a metal detector to dig up some metal boxes with Magic Carpets for the colony. What does any of this have to do with clue scrolls, you might ask? Well, after the quest, you can use said metal detector to locate a rare Elite Clue Scroll with great rewards. You are never told this, ever. Furthermore, the Elite Clue Scroll is buried in one of four obscure locations that you would not likely go to otherwise while wearing the device. How anyone found out about this is a mystery to this Troper.
One quest taking place in Morytania, a land ruled by the undead, involves you finding a cure to a disease in Mort'ton. Afterwards, the diary that you start the quest by reading can be given to an Apothecary in Varrock for some Herblore experience. You are never told this. Furthermore, Varrock is not located in Morytania, and the Apothecary is used only for a minor role in an easy freeplay quest. Guide Dang It.
The "Elemental Workshop III" quest features an insanely complicated, 3D sliding puzzle that is nearly impossible to solve without a guide. And even with a guide, it still takes ages.
Want to know how to dodge Vanstrom Klause's extremely dangerous darkness attack? The game tells you to look away from him when he telegraphs it, and you'd be forgiven for assuming that means to position your character facing away from him. Nope, just doing this will probably get you hit with around 500 unblockable damage. It actually means to angle the camera in such a way that it's not looking at him. Not only is this hard to figure out, but you only get a second or two to react to the incoming attack, and winning the fight without knowing how to dodge this is something only the highest level players can do.
Ongoing example: in a recent quest (released in December 2012, this being written in March 2013), you are having a Tz Haar translate old texts for you, but you don't have him on hand to translate the last set. That's ok, because by this point it's the boss fight of the quest, so you can just complete it. Well, a Jagex moderator has confirmed that it is possible to translate the text. After months of searching, the community has been given the following information: there is a Ga'al (basically, a Tz Haar born as a blank slate instead of fully matured) who escaped the Tz Haar city wandering around Runescape, but he's really good at disguising. If you find him, he'll take you to the area and translate it for you. To trigger his appearance, you need to meet a set of conditions which are presently unknown. Some ideas include changing your title to be Tz Haar themed, a Ring of Stone (which turns you into a pile of rocks, as Tz Haar are rock creatures), obsidian armor from the quest, a Ring of Visibility (it's been confirmed that you need "more than this ring"), all of the above. And we have no idea where to look.
Arcanum: Of Steamworks & Magick Obscura. Due to the wide open sandbox, the complex lore of the setting, and the vast number of side quests, this trope is inevitable. It is nearly impossible to find all the side quests without some kind of guidance, and there are many side quests for which the game does not give sufficient information on how to complete. For example:
There is a huge, complicated sidequest where you have to make certain offerings to certain altars in a certain order. The game never tells you where said altars are and many of them are so far out of the way that no player will just stumble into one. One of these altars is so deep in a mountain range that, even if you do have the location, it is very difficult to get your character to that spot. Also each altar requires a specific offering, each of them being a completely innocuous item that can be easily mistaken for Vendor Trash if the player does not know what it's for. It's even worse if the game only provides enough of a particular offering to use in this puzzle.
In order to help Magnus find his lost clan, you must first complete a side quest for a dwarf to get the location of a mysterious clanhold, then you must obtain a keystone to get inside said clanhold. Problem is that the keystone is a reward obtained at the end of a very complex and completely unrelated side quest near the end of the game that is only available if the player is opting for the good ending!. Not only that, but the game never tells you what the keystone is for. All the player knows at this point is that the clanhold is locked with no hint as to how to open it, and that they have a rock taking up inventory space. The game also does not give the player any reason to have Magnus AND Loghaire in your party when you enter the clanhold, causing many players to miss out on a very important dialogue where Loghaire makes Magnus chieftain of the Iron Clan.
Want one of the best (so much that some consider it a Game Breaker) NPC companions in the gamr? Then you need to know exactly what to do when entering a certain city, where one of the citizens is kicking a wounded dog on the ground. That dog is your future companion if you manage to tell the citizen to stop kicking the pooch. The only problem is that the already wounded dog is kicked constantly and can very easily die before you even know anything happened if you don't run straight away to the scene of action as soon as you enter the area.
The Witcher 2: Assassins of Kings features an essentially hidden sidequest, "From a Bygone Era", which allows you to either reset your skilltree or get the best additional weapon, and one of the three Dragon Scales in the game. You must find a rundown shack in Chapter 2, near the Kaedweni camp, which is tricky if you're playing Iorveth's path, in which case you only visit the area once, and blast some unremarkable barrels behind it to reveal a cellar entrance. Then you must solve a puzzle which requires information from the gravestones in the backyard. This gets you a book containing some gibberish words. You must show it to Bras of Ban Ard in Chapter 3, who will explain exactly once in what order the words must be used to pass the Guardian that you can find in the sewers of Loc Muinne. This information is not recorded in your Journal and you can't ask again, making the Guardian's puzzle a very frustrating process. Finally you must pass a relatively simple puzzle to reach the Operator, who will either reset your skilltree, or end up being possibly the hardest bossfight in the game, depending on what you want from him.
At one point in Slime Forest Adventure, you have to mine the hills for a certain kind of rock. The author wanted each attempt at mining to trigger a random encounter. (It's an Edutainment Game, and random encounters are the main tool for training the player.) However, it's been repeatedly established that there are no slimes in the hills. The end result is that mining while standing on a hill tile results in a generic "Nothing found" message. You have to be standing on another type of tile, facing the hill you want to mine, before you can trigger the random encounter, which you have to win in order to get your rock.
Famously in the original Dungeon Siege game there is a secret 'chicken level', which can only be accessed by placing three completely unassuming items on pressure plates in the MULTIPLAYER map! You need:
The completely normal in every way level 1 knife that your character starts with in singleplayer. You only get one of these (per character), so if you replace it (as any character would as they level up) then tough, start again!
An item from a HIDDEN secret mini-dungeon in an otherwise normal quest area in the singleplayer campaign.
A quest reward book from an extensive quest chain in the multi-player campaign.
The book gives a very cryptic riddle which vaguely directs the player to an area of the multiplayer map he'd never usually go anywhere near. The entrance to it is only opened if you have the book. The riddle also very cryptically refers to the level 1 knife and the item from the hidden dungeon, and rather less vaguely instructs the player to place all three items on the respective pressure pads to 'start the trial'. The trial turns out to be slaughtering a load of chickens (one of which named for the lead developer, Chris Taylor) who start with ridiculous amounts of health (but do very little damage). Once defeated, the player receives humorous and massively overpowered loot, including a gun that fires chickens.
The chicken level in Dungeon Siege is a rather obvious reference to The Cow Level in Diablo II, and previous contributors should be ashamed for failing to mention it in this trope yet.
French indie RPG OFF contains a puzzle that is impossible to solve without consulting a guide.
The Megaman Sprite Comic game has this. Got the bad ending? Don't know what you have to do? Get this; you ACTUALLY HAVE TO STAY OFF THE GRASS FOR EVERYTHING UP UNTIL THAT POINT.