* AlternativeCharacterInterpretation: Even unseen characters are subject to this. To list:
** [[spoiler:Is Isaac a victim, a sacrifice, the spawn of the devil (possibly even the AntiChrist), or MessianicArchetype?]]
** [[spoiler:Is ??? Isaac post-suicide? Is he his own person?]]
** [[spoiler:Are the other playable characters alternate personalities? If not, are they related to Isaac? Is ??? one of them?]]
** [[spoiler:Is Mom a religious zealot, just insane, or both? Did she go insane from religion, raising Isaac, or her husband leaving them?]]
** [[spoiler:Is God [[GodIsEvil evil]] or [[GodIsGood good]] in this game? Did He have Mom sacrifice Isaac for fun, as a test, or because he was the Anti Christ? Did He even ask her to do it or was she just imagining things? What is His relation to the Angels?]]
** [[spoiler:Is Satan trying to protect Isaac or awaken him as the Anti Christ? Does he just see Isaac as a customer and tries to get more payment in the Sheol path? How is he related to Mega Satan? Then there's the signs that he may even represent Isaac's Dad in some way.]]
** [[spoiler:Is the Lamb supposed to be a demonic Jesus? A representation of whatever Mom "should" have sacrificed? Some other, skeletal, horned version of Isaac himself? Or just some other demon monster? Its general placement as the boss of a location accessed after Sheol is beaten and Satan himself is killed raise a lot of questions, especially seeing as it is the "negative counterpart" to ???.]]
** [[spoiler:Did Isaac's Dad leave because he was a {{Jerkass}}, didn't feel like he could be a good family man, or to get away from his mentally unstable wife, who may have had several miscarriages?]]
** [[spoiler:Is the ending where Isaac turns into a demon good or bad? Is Isaac finally happy?]]
** While the final ending provides some answers, it does raise its own questions. [[spoiler:To what extent did Mom abuse Isaac, if at all? While her trying to kill him is a hallucination, the abuse implications in many items is hard to ignore. Why did Isaac's parents split and whose fault is it truly?]]
* AntiClimaxBoss:
** Mom's Heart/It Lives will rarely pose a serious threat to anyone who is good enough to reach it. It is considerably [[BulletHell more of a challenge]] in ''Rebirth'', however.
** The red champion version of Mom looks impressive, but is actually far easier to beat due to her greater attack speed and lack of MookMaker abilities. Players can just dodge the telegraphed foot attack and retaliate, occasionally dodging a bullet spread from her eye. It can be troublesome if you have one of the Fetus items, however, as you have to time them very carefully to land a hit and thus the fight drags out for much longer.
** Satan in ''Rebirth''. While his fellow {{Final Boss}}es received new tricks which generally made them much more impressive than they were in the original game, Satan stayed more or less the same, with only a couple of new attacks added in only one of his phases, which are quite similar to the attacks he already had. Add the increased potential for powerful item combinations, and he just CantCatchUp.
** Ultra Greed in ''Afterbirth'' is undeniably a fun battle, and it does take a while to win thanks to his scaled health gimmick. That said, given how easy it is to collect powerful items over the course of the run, coupled with the fact that Ultra Greed's attacks are telegraphed well in advance, he'll only pose a real challenge to characters with low health (i.e. [[spoiler:the Lost]]) or those with low speed attacks. A patch buffed the health of his giant coins, making them more likely to survive the player's attacks, which means he gets to summon more mooks and recover more health (not to mention the bombs, though those are the easiest to dodge). He also TurnsRed as his health drops, making the fight much more challenging. Greedier Mode in ''Afterbirth Plus'' fixes this further by giving Ultra Greed a second phase, in which he throws explosive coins all over the place while leaping to cause rock shockwaves and firing brimstone lasers out of the golden doors. A much faster-paced and hectic battle... that comes with its own weakness -- as most of Ultra Greedier's attacks are explosive-based, the Pyromaniac and Host Hat items rocket him back into Anticlimax.
** [[spoiler:Delirium]] zig-zags on this. Against most characters, [[spoiler:Delirium]] is pretty easy to beat as long as you have good damage and a fair amount of spare health. With certain combos, he can be killed faster than [[spoiler:Mega Satan]]. Against the GlassCannon characters like [[spoiler:Keeper and the Lost]], his constant teleporting (frequently into you for unavoidable damage) and BulletHell can make the fight almost a LuckBasedMission.
* AudienceAlienatingPremise: It's a NintendoHard game about a little boy whose religious nutcase of a mother wants to sacrifice him to God, loaded to the brim with BodyHorror, child abuse, religious imagery, and poop. Edmund himself figured that the premise alone would send potential players packing and [[ItWillNeverCatchOn fully expected the game to crash and burn]]. [[SleeperHit It didn't.]]
* AuthorsSavingThrow:
** [[http://bindingofisaac.com/post/118142172929/mega-update-afterbirth-5 Edmund admitted]] that [[spoiler:The Lost]] was infamously too hard to play, and he has received a major buff in ''Afterbirth'': he now has spectral tears, letting him fire through obstacles, and he starts with the D4, allowing him to reroll all his items in the hopes of getting better ones. A later patch buffed him even further: [[spoiler:Holy Mantle is now an unlockable starting item for him, which many players consider to be '''THE''' most valuable item to get as the Lost, as it turns him into a two-hit wonder rather than one-hit. Although this clashes with the D4 if you have both, since starting with one of the most powerful items for the Lost means there are very few rolls you could get that would overall improve your loadout. Additionally, the Missing Poster Trinket now turns your character into The Lost if you die while it's equipped (after unlocking The Lost). This basically means you don't have to start a game as The Lost in order to unlock his stuff.]]
** After some rather major internet outrage accusing Edmund of not caring about the fanbase and "throwing a temper tantrum" due to a patch adding extra items in that were promised to be put in the game in the first place, [[https://www.reddit.com/r/bindingofisaac/comments/3rjx77/elephant/ Edmund made this post]], elaborating that the items weren't originally in the game due to an unexpected glitch, and he meant no ill-will towards anyone in the community.
** The ''Afterbirth'' AlternateRealityGame was an example of this. In ''Rebirth'', Edmund wanted the community to work together to unlock something in the game, but in the end, it was data-mined. In ''Afterbirth'', the unlockable content ''wasn't even patched in'' until the game was finished.
** After some backlash concerning nerfing the Stopwatch, Edmund [[https://twitter.com/edmundmcmillen/status/667816523268907008 tweeted]] asking the community what items they would like to see buffed. As of December 6th, a patch buffed several bad items (for example, the Scissors are now a two room charge, the Friendly Ball is now a three room charge, and the most important of all, the Stopwatch is no longer a Special Item, and activates when the Holy Mantle is triggered), fixed several bugs, and ''finally'' reworked [[ScrappyMechanic sacrifice rooms]].
** As stated in BrokenBase, ''Afterbirth+'' as a whole was initially released to mixed reactions, particularly due to the difficulty spikes that bordered on just plain unfair at times. However, Edmund listened very closely to fan feedback over the next two months and tweaked the game accordingly, removing much of the FakeDifficulty and buffing underwhelming items. These tweaks have been very well-received by the community, and now ''Afterbirth+'' is largely considered a good follow-up to ''Afterbirth''.
** The second Booster Pack for ''Afterbirth+'' buffs Angel Rooms, with them now giving items more frequently and being able to spawn with multiple items which you would choose between.
* [[AwesomeBosses/VideoGames Best Boss Ever]]:
** Loki, an always-smiling demonic baby, is quite preferred over [[ThatOneBoss Monstro II]] as the boss of the fifth floor. They even call him "Mr. Cool" in the credits.
** [[spoiler:Satan, boss of Sheol, is the most complex boss fight in the original game and is the only boss to have multiple complete health bars. Before he even lets you fight him, he sends out one of The Fallen at you, and once you beat him, he breaks out of the statue and goes berserk, using updated versions of The Fallen's attacks. And after you beat him... he gets right back up, flies offscreen, and uses Mom's battle strategy as the fight becomes more fast-paced with him constantly stomping on the floor. After you beat him here, he finally falls and gives you Ending 11.]]
** [[spoiler:''Rebirth'' naturally tops Satan with Mega Satan, who combines Giant Hands of Doom, mixes in minor elements of BulletHell, and summons at least thirteen {{Degraded Boss}}es with a grand total of eleven phases. And then he still has one more form left, where he goes all-out with the BulletHell in a last-ditch effort to kill you.]]
** [[spoiler:''Afterbirth''[='=]s Ultra Greed due to having a unique gimmick involving coins that, if not destroyed, can unlock doors that summon enemies, and Hush due to being the game's biggest example of BulletHell but this time in a 2x2 room. Both also have damage resistance which scales depending on the damage you're doing, so even if you're on the most powerful run of your life, they still won't become an AntiClimaxBoss and die in one hit.]]
** In ''Afterbirth+'', we have [[spoiler:Delirium, the ultimate boss of the game. While he starts in his true form, he starts mimicking the other bosses in the game, including other Final Bosses, with absolutely insane attack variants]].
* BreatherBoss: Now has [[BreatherBoss/TheBindingOfIsaac its own page.]]
* BreatherLevel: Even during the BrutalBonusLevel, there will occasionally be rooms with only a fly or a pair of helpless grubs, which still recharge your special item and have a chance to drop items. There will also always be some empty rooms, and it's possible to spend quite a long time in the arcade with virtually no chance of death.
* BrokenBase: Now has [[BrokenBase/TheBindingOfIsaac its own page]].
* CrossesTheLineTwice:
** Literally all of the humor qualifies. The best example is probably the infamous "Yay, cancer!" -- a description of a trinket that's literally a tumor and increases the rate of fire.
** The Aprils Fool challenge has you go through the game with several interface screwups such as a broken map and items that are disguised as other items. Coins are golden hearts, red hearts are actually coins, and so on. To top it all off, you'll soon come across [[ThatOneBoss The Bloat]]. And [[RecurringBoss The Bloat]], and [[RunningGag The Bloat]] ''[[AscendedMeme again]]''. That every boss is replaced by this loathed opponent does at least give the annoyances of this challenge a touch of hilarity. The fact that you're basically immortal in this mode thanks to coins being soul/black/gold hearts only adds to it. Unless, of course, the game decides to kill you by [[PressXToDie giving you a card that turns out to be Suicide King or making you roll Plan C with your spacebar item]], in which case you will likely alternate between laughing and cursing out the RandomNumberGod.
* DarknessInducedAudienceApathy: While downplayed due to the game CrossingTheLineTwice with a huge helping of BlackComedy thrown in, a small but fair amount of players don't like the ''very'' dark undertones that the game offers including AbusiveParents, anti-religious themes, and suicide. The true ending where it reveals that [[spoiler:it's a DyingDream]] does not help much.
* DemonicSpiders: Now has [[DemonicSpiders/TheBindingOfIsaac its own page]].
* DisappointingLastLevel:
** Compared to the Halloween Update's [[spoiler:Sheol]], which tested your skills with the base game's items and had an awesome boss at the end, Wrath of the Lamb's [[spoiler:Cathedral]], which further tested your skills and had a brutal boss at the end, and a later update's [[spoiler:Chest]], which essentially starts out with four Item Rooms and contains mostly bosses, ''Rebirth'' gives us [[spoiler:the Dark Room]], meant to be the demonic counterpart to [[spoiler:the Chest]]. It succeeds in all the wrong ways, with the level starting out with four Red Chests instead of trading four keys for four items and having much more unfair rooms. Its only redeeming counterparts are a great boss fight at the end and the fact that non-Red chests still pay out with items.
** ''Afterbirth'' added an optional level named "???" that unlocks one of the last endings once it is cleared for the first time. However, it is just a single room with a few items and then the BonusBoss. And yet it gets [[LongSongShortScene a song that lasts for over 2 minutes]]. Not quite what people expected at release.
** ''Afterbirth+'' added what's meant to be the ultimate final stage and boss of the game. It's [[spoiler:just [[AllTheWorldsAreAStage a mash-up of previous levels and bosses]]]]. [[spoiler:The Void]] and its boss, [[spoiler:Delirium]], ''are'' fitting narrative-wise, but it all still feels very underwhelming to a lot of people.
* EarWorm: Try finding a player that doesn't have [[https://youtu.be/FwbK0Y1qnOY Sacrificial]] stuck in their head. There's also the [[https://youtu.be/p3Wm1hH5FFs 8-bit version]] that plays in Arcades, which might be even catchier.
* EndingAversion: Ending 20, the real final ending to the game, [[spoiler:just [[DepartmentOfRedundancyDepartment reaffirms what was shown by the previous few endings]]. There's [[OnceMoreWithClarity more clarity]] to it, [[MindScrewdriver yes]], but it doesn't reveal anything new either, is still [[LeftHanging quite open-ended]], and even closes the story at the same point Ending 17 did]].
* EnsembleDarkhorse: The [[http://platinumgod.co.uk/dark-bum Dark Bum]] from ''Rebirth'' quickly became one of the most wanted items. When it was severely nerfed, there was fan outcry for him.
** Sissy Longlegs, while not a very powerful item, [[UglyCute is cute in her own way]]. Her description "she loves you" tends to give her a free pass on rerolls.
** Bumbo from ''Afterbirth'' has won a lot of fans over with his array of rather useful abilities. The fact that he grows by collecting money, which tends to be rather useless later on, also helps. Edmund seems to have been very aware of his popularity, as he is now receiving his own SpinOff game.
** Dry Baby is also considered a god-like item due to its ability to block pretty much all shots and damaging every enemy in the room each few shots it blocks.
* FandomBerserkButton: Using the Flash Filter in ''Rebirth'' will often get people to mock you for it, particularly those who use Website/FourChan. This is most likely because of how blurry the filter looks compared to the non-filtered game, and the fact that the filter was only added in as a joke against the people who hated the pixel-art style of the game.
* FanNickname: [[spoiler:Mega Stan for Mega Satan]].
* GameBreaker: Has [[GameBreaker/TheBindingOfIsaac a separate page.]]
* GeniusBonus:
** When under the effects of Whore of Babylon, your character leaves a small puddle of blood rather than the usual puddle of pee left at low health every time you enter a room. This may be a reference to past conceptions of what periods were (a curse due to Eve's actions of original sin) or even to the Biblical passage introducing the Whore of Babylon, "...and I saw a woman sit upon a scarlet coloured beast..."
** Azazel is a fairly commonly referenced [[NamesToRunAwayFrom/DemonsOrAngels demonic name]]. But it's also [[http://en.wikipedia.org/wiki/Azazel a word for a sacrificial scapegoat]] -- Azazel, like Isaac himself, is named after a sacrifice.
* GoddamnedBats:
** Knights and their many variants are hard to hit, since they're invulnerable in the front and have unpredictable movement patterns. Some even turn to charge you. Past a certain point, piercing is practically required to survive. It certainly doesn't help that there's a boss version.
** Hosts take cover and shoot 3-way shots. Sometimes weird maneuvers must be taken for them to show up. There is a red host variation which cannot take cover, but it shoots a 5-way spreadshot and fires more often.
** The many varieties of flies fit the trope better. Especially the ones that shoot at you, or explode in a flurry of bullets upon death.
** Similar to the flies, the many variants of spiders fit this as well. Not that hard to kill (once you learn the basics of dodging), but they are on every floor, many bosses and some mooks spawn them, and they are ''just'' random enough in movement to chip damage you to death over the course of a long run. Good luck trying to kill them with the Ipecac or Fetus in a Jar.
** Lil Haunt, the mook version of The Haunt, is an extremely cheap enemy. Their movement pattern is designed to lead you, which makes it very easy for them to corner you (but also extremely easy to control them if you know this). They have a bullet attack which has no tell or consistency. They are tougher than most mooks their size. Finally, they make the boss fight against The Haunt that much more annoying.
** Wizoobs, the ghost enemies that spend most of their time phased out of existence except to spray a hail of bullets in your face. Their attack isn't too hard to dodge, but they have a boatload of health, don't stay tangible long enough for you to deal any meaningful damage, and tend to spawn in packs of ''six'' or more. No matter what items you have, they will take a disproportionately long time to kill. ''Afterbirth'' adds in Wizoobs which shoot ''Brimstone'' to the mix, only making their infamy worse.
** Bonies. Not terribly dangerous or tough, but their bone throw has absolutely no tell, and they will use it almost without fail if you try to line up with them to take a shot, making it very likely that one of them will hit. They're also some of the few enemies that Azazel has trouble dealing with, as his short range is pretty much an invitation for a point-blank bone to the face.
** By the time you reach Chapter 6: Headless Horseman Heads. Their size, speed, and health make them take a while to kill (unless you're ridiculously overpowered), they fire three-way blood shots, and they often spawn in groups of two or three, or are accompanied by either [[DemonicSpiders Demonic or Holy Leeches]]. By this point in the game they aren't really that dangerous, but they're certainly ''annoying'' to fight through.
** Fat Bats are both a literal ''and'' a metaphorical example of this. They come with a boatload of health, have unpredictable bullet attacks with no tell, and try to avoid your shots. On the other hand, they're also slow and don't shoot very often (and when they do, it's relatively simple to dodge). As a result, they're not exactly dangerous so much as tedious to fight.
** Imps. Any time they're not casually avoiding your shots they're firing a very fast barrage of shots directly at you. It's not uncommon to spend half a minute just trying to kill one, especially if it's a champion version.
** Stonies cannot hurt Isaac, but what they can do is block Isaac's shots at other enemies, which gets annoying ''very'' quickly. Especially since Stonies are {{Invincible Minor Minion}}s and will only die when every other enemy in the room has died. It didn't take long for Edmund to {{Nerf}} them by causing them to have to stop and catch their breath every five seconds, which downgraded them from DemonicSpiders.
** Mushrooms in ''Afterbirth+''. They have above-average health along with boosted defense when they take cover, and tricky Clotty/Clot shot spreads. That alone wouldn't qualify them for this, but as Host variants, they can spawn from breaking skulls. Oversight or not, this means that destroying skulls with a break-on-touch ability is no longer a guaranteed safe option (Hosts do not deal contact damage, but Mushrooms do), which limits an easy way to acquire tarot cards, runes, black hearts, and Dry Baby/Ghost Baby.
* GoddamnedBoss: So goddamned many of them that it has [[GoddamnedBoss/TheBindingOfIsaac its own goddamned page]].
* GoodBadBugs: It has so many entries that it now is [[GoodBadBugs/TheBindingOfIsaac its own page]].
* HarsherInHindsight: All of the Guppy-related items were inspired by a real cat who [=McMillen=] owned -- "owned" because [[http://bindingofisaac.com/post/95782104184/9-lives/ the real Guppy passed away in August of 2014]]. Where this trope comes in is that quite a few of these items clearly show that the cat in question is dead...
* HypeBacklash: Considering that ''The Wrath of the Lamb expansion'' available for the original version of Issac was absolutely enormous and dirt cheap, many fans thought that ''Afterbirth'', the first expansion for the remake, would be comparable to WOTL. It is nowhere near that size, which many fans have felt ripped off by. While many praise new additions like the genuinely interesting (if somewhat buggy) character Lilith, the fantastic and fun Greed Mode, and many of the new items being very fun to toy around with (and boasting even more tasty synergies to fool around with), there are a ''staggering'' amount of issues[[note]]The absolutely massive amount of bugs, needless difficulty increase from ''Rebirth'', constant patching (to not fix the bugs but instead make the game tougher), the disappointing challenges and transformations, the 109 incident and Edmund's incredibly poor handling of the situation[[/note]] that have left a good portion of the fanbase extremely upset and disappointed.
* InternetBackdraft:
** When the game was barred from release on the [[UsefulNotes/Nintendo3DS Nintendo eShop]] due to the religious content, ''all hell broke loose.''
*** Thankfully no longer the case as of 2015. Nintendo's former head of indie relations, Dan Adelman, managed to reform Nintendo's outdated and restrictive eShop policies prior to leaving the company to go independent, which finally allowed ''Binding of Isaac: Rebirth'' to see an official eShop release on the New 3DS and UsefulNotes/{{Wii U}} in an uncut state.
** The ''Afterbirth'' AlternateRealityGame, or rather [[spoiler:what was initially believed to be one. After Edmund and Tyrone (the programmer) teased the community with what seemed like another ARG, it turned out there was none. The missing content from the game was just added after 109 hours, with a patch that on top of that severely (if briefly) nerfed Azazel and a few powerful items.]] Cue community's complaints, which mostly died down [[spoiler:after the real ARG.]]
* ItWasHisSled: Let's just say that anything in the game that can be considered a spoiler tends to fall into this territory very quickly. The existence of [[spoiler:??? and The Lost]], for instance, tend to barely even be treated as spoilers by the community.
* MemeticBadass: Certain items have this reputation. However, said items are generally useless or arguably downright harmful.
** Before ''Rebirth'', Abel (a mirrored familiar with the power of basic familiars) was the most common example, but since then, it had to share the spotlight with Aquarius (tracks low-damaging trail of tears on the ground).
** Bob's Brain (an item that is a bomb that can be shot towards enemies, [[SplashDamage whether or not]] [[YetAnotherStupidDeath you want it to]]), best item in the game!
** Nothing stands between Bumbo and his coin. Not even [[spoiler:Hush]].
** The [[ResetButton Glowing Hour Glass]] is gaining a reputation as being [[TheAllSolvingHammer the solution to literally everything.]]
** On the bosses' side, there's The Bloat. While this game certainly doesn't skimp on the [[ThatOneBoss brutally difficult bosses]], none of them (not even most of the {{Final Boss}}es) have obtained the same reputation for destroying runs as The Bloat has.
* MemeticMutation:
** One of the most popular emoticons on Twitch is [=BibleThump=], which is Isaac crying.
** "It's not a won run yet!" tends to be used for very powerful runs, which came about due to Northernlion consistently saying it for runs which were very easy.
** People messing around with the intro narration has resulted in [[https://www.youtube.com/watch?v=HMR0Aldn6WU The Isaac of Isaac.]] One of the Community Remix devs is currently making a mod that replaces all item textures with Isaac, turning this masterpiece into a playable experience.
** [[AC:CHUB DISLIKES SMOKE!]][[labelnote:explanation]]The Rules Card item is infamously useless. It's supposed to give the player hints, but not only is the hint in question (which seems to be the only thing the card ever pays out with, despite there being confirmed to be a ton of other, more useful hints for other things such as BossRush) referring to something [[FeedItABomb rather obvious]], very few people play the game without visiting the wiki anyway.[[/labelnote]]
** Yay, Cancer![[labelnote:explanation]]Cancer is widely regarded as one of the best trinkets in the game, as it effectively doubles your tear rate and therefore damage output. The BlackComedy of getting cancer being one of the best things that can happen to you in this game has not been lost on the fanbase.[[/labelnote]]
** [[StupidSexyFlanders Ultra Greed's Ass]] [[labelnote:explanation]]The FinalBoss of Greed Mode, Ultra Greed, has, for whatever reason, a very well-detailed butt. This has not gone unnoticed among the community.[[/labelnote]]
** 109. [[labelnote:explanation]]Before the November 4th patch, the Greed Machine used to max out at 109. Many believed that this was a code and part of the ARG. Due to the amount of speculation regarding the number before the patch, and the controversial reveal that it was a countdown, it has since become (in)famous among the community.[[/labelnote]]
** Are you enjoying the steak? Remember to chew it slowly or else...[[labelnote:explanation]]Edmund got very angry when dataminers leaked the secrets of Rebirth. Both he and Tyrone went into an interview and said that the community "swallowed a hundred dollar steak in one bite", which lead many people to ironically refer to the game as "the steak". People (especially {{Imageboards}}) started joking about how Edmund is nerfing the items just to ruin the fun, or in other words, "not letting you eat the steak too fast".[[/labelnote]]
** Shh, don't let Edmund hear about x, he might nerf it...[[labelnote:explanation]] ''Afterbirth's'' release was infamously followed by a series of patches focused on needing items. As a result, fans often jokingly hesitate to refer to any item as "overpowered" for fear that Edmund might hear about it and {{Nerf}} that item in the next patch.[[/labelnote]]
** Two words: "Dank Depths".[[labelnote:explanation]]The new alt floor of the Depths, introduced in ''Afterbirth'', which quickly became a joke.[[/labelnote]]
*** For WebVideo/{{Vinesauce}} fans: [[https://www.youtube.com/watch?v=gjvFLuJFkgU Dank Dopths]].
** FUCK BLOAT[[labelnote:explanation]]As shown in ThatOneBoss below, the game has plenty of tough bosses, but the Bloat is probably the best known and most detested, to the point where Reddit has ''an entire subreddit'' ([[https://www.reddit.com/r/FUCKBLOAT/ r/FUCKBLOAT]]) devoted to complaining about him.[[/labelnote]]
** SHAKA SHAKA DING DING[[labelnote:explanation]]The "lyrics" of [[https://youtu.be/aLP3lByCmkA Shadowdance]], Antibirth's theme for Sheol. It quickly became memetic on Reddit, to represent the hype for the mod and Antibirth as a whole.[[/labelnote]]
* MoralEventHorizon: Isaac's mom crosses it at the start of the game when she tries to murder her own son.
* MostAnnoyingSound: Isaac's 'hurt' sound when he takes damage has no variation, and if you have to hear it several times in a row, it quickly becomes grating.
* MostWonderfulSound:
** The high-pitched cue when you pick up a dime.
** The jingle that plays when finding a Secret Room in either version. The ''Rebirth'' one is notable enough that it plays when selecting ''Rebirth'' on the New 3DS menu.
** The narrator calling out the name of any pill or card used, especially if it's one with a beneficial effect. The [[ArousedByTheirVoice really nice voice]] doesn't hurt.
** The angelic choir when you pick up a Soul Heart, or the triumphant note of picking up an Eternal Heart.
** The combination of "pinball bonus"-like sounds when you use a pill with a positive effect.
** The sound of an Angel or Devil Room opening up after a boss kill. [[spoiler:Unless you have to fight Krampus, that is.]]
* {{Narm}}: The TrueFinalBoss of ''Rebirth'' is undeniably awesome in every way...except for his name. [[spoiler:His name is Mega Satan]], which, while intended to make him more awesome, leads to this instead.
* NauseaFuel: The environments and enemies are all really gross, from the giant turds lining the floors, the enemies that look like giant anuses firing out laser beams, grotesque monsters lined with all manner of horrific markings... ich. The Rebirth remake adds more details, including things like tiny maggots crawling around the floor in large numbers.
** The Womb's music track in ''Rebirth'', "Viscera", contains... indescribable ''fleshy'' sounds that might be a little unnerving to some players.
** The [[spoiler:Scarred Womb]] in ''Afterbirth'' may be the most nauseating environment to look at in the entire game. The name should sum it up quite well.
** There is a "Gulp!" pill, which destroys trinkets and adds their effects to you permanently - Presumably by swallowing them. There is a Used Diaper trinket. [[{{Squick}} Draw your own conclusions.]]
* NightmareFuel: [[NightmareFuel/TheBindingOfIsaac It has its own page.]]
* RescuedFromTheScrappyHeap:
** Samson in ''Rebirth'', following his transition from the original game. While he was originally despised for having low health and having an ability which lasts only one room, the remake greatly increased his health and made his ability not only easier to achieve, but also last the entire floor.
** [[spoiler:The Lost]] in ''Afterbirth''. Originally a OneHitPointWonder whose only special ability was flying, the expansion greatly buffed him ''three times''. He now starts with the D4, spectral tears, and the Holy Mantle (though the latter item must be unlocked first), which makes the game significantly less frustrating for those playing as him. Another patch made his unlock process ''significantly'' easier to accomplish, which no longer makes it a GuideDangIt affair.
* ScrappyMechanic: Now has [[ScrappyMechanic/TheBindingOfIsaac its own page]].
* ScrappyWeapon: A few.
** My Reflection is a particularly infamous one, as it just makes your tears boomerang around wildly, cutting your range and making it hard to aim. Some combinations using it will screw you even harder, such as combining it with IPECAC or Bob's Rotten Head, causing your explosive projectiles to boomerang right back at you. Even worse is that the Suicide King challenge in ''Rebirth'' sticks you with the My Reflection + IPECAC combo for the entire run. It works surprisingly well with Azazel, however, as it's one of the few items that increases his otherwise short range.
** Bob's Brain and BBF in ''Rebirth''. There's nothing worse than being in the middle of combat and having them respawn and explode on top of an adjacent enemy, catching you in the blast. Sometimes, BBF can even damage you as soon as you enter a room! Bob's Brain, at least, was toned down a bit in Afterbirth, as it now can't be fired for a few seconds after it spawns or after you enter a room, preventing surprise explosions.
** The Cursed Eye. While the quadruple charge shot is nice, if you are hit while charging the shot, you will be teleported to a random room. This makes fighting bosses very problematic, as even one mistake can warp you away and ruin all of your progress. Fortunately, this drawback is easy to work around, and can even be beneficial in some circumstances. Most notably, allowing you to take a free item from the Boss Rush room.
** The Stopwatch, which is frowned upon for either being too powerful or too weak of an item, depending on what version of the game you're playing. In ''Rebirth'', it is a huge GameBreaker which slows down enemies and projectiles for the entire game. In ''Afterbirth'', however, the slowdown effect not only lasts one room, but only activates if you take damage.
** ''Rebirth'' also gives us Soy Milk, which, at the cost of slashing 80% of your damage and tear size, ''massively'' boosts the firing rate of your tears, to the point that a starting Isaac with Soy Milk has enough of a fire rate to shoot 30 tears per second. Unfortunately, the game has a hardcoded limit of ''15'' tears per second, meaning that while it's technically a bit more [=DPS=] than your default tears, that's only if you make ''every shot count''. Given the game's enemies and their erratic movement patterns, making all your tiny tears hit their mark so the damage output is at least decent is a pain in the ass. The [=DPS=] is so poor, all bosses become {{Marathon Boss}}es, and even ''[[TheGoomba flies]]'' take a lot more shots before they're down. And to add insult to injury, it's a special item, so once you see it, your chances of a ''really'' good item in your current run fall dramatically! Only once you gain a '''lot''' of DMG ups or synergize Soy Milk with other certain items does it become a GameBreaker, due to its high firing rate carrying over. Fortunately, in ''Afterbirth'', Soy Milk is no longer a special item, meaning that it no longer interferes with your ability to get really good items just by showing up.
** Of all items, Dr. Fetus is this in ''Rebirth''. In the original, it was seen as a borderline GameBreaker due to its tremendous damage output, but also carried a [[DifficultButAwesome high chance of damaging yourself]]. In ''Rebirth'', Dr. Fetus bombs had the self-damage reduced, but also suffered a massive damage drop, meaning that it now fails to consistently OneHitKill many normal enemies and kills bosses ''very'' slowly. It did also receive an increased fire rate, which theoretically makes Dr. Fetus an overall damage upgrade, but in practice tended to cause bombs to knock each other around -- often into ''the player's face''. It doesn't help that fellow explosive attack Ipecac has the same self-damage, but deals much more damage to enemies. Fortunately, ''Afterbirth'' restored Dr. Fetus to its former glory.
** ''Afterbirth'' also brings us the [[ExactlyWhatItSaysOnTheTin Glass Cannon]]. On release, it reduced the user to half a red heart, but gave you an on-command massive tear with scaling (but always high) damage. However, as of the November 4th 2015 update, it now reduces you to half a heart -- including soul hearts and black hearts -- turning the user into, appropriately enough, a GlassCannon. To say that people are not amused is a massive understatement.
** The Butter Bean introduced in ''Rebirth''. It's a spacebar item that only has the effect of producing a small fart that can knock back some enemies. At least it recharges spontaneously, and in ''Afterbirth'' it can deflect bullets. [[spoiler:''Afterbirth+'' removes it from this category, as swapping it with another item repeatedly can transform it into "Wait What?", an identical-looking bean that loses the fast recharge time in exchange for creating a circle of rock waves around Isaac.]]
** The Wiz, which doubles rate of fire at the cost of sticking you with the "R U A Wizard" effect for the rest of the run, forcing you to shoot diagonally. Given that the game is based around being able to shoot in the cardinal directions, meaning that "R U A Wizard" is generally considered a negative effect, it's not a very popular item.
** Tiny Planet is in roughly the same boat as Soy Milk. Sure, it's a stat upgrade and has some interesting synergies, but the orbiting tears on their own have short range and are nigh-impossible to aim, meaning that players tend to avoid it like the plague. It doesn't help that the effect combines badly with certain strong items, such as Mom's Knife and Dr. Fetus.
** Curse of the Tower is a passive item that spawns Troll Bombs randomly around the room each time you take damage. Which usually results in the player being blown up and taking even ''more'' damage, especially in half-size rooms or if they're unlucky enough to also have an item like Bomber Boy or Scatter Bombs. It also makes Devil Beggars and Blood Donation Machines virtually unusable, as they tend to get blown up immediately after one use.
* SelfFanservice: Some fans have a habit of portraying the playable characters as adults without the SuperDeformed art style, often just keeping two traits about them: Their starting accessories/hair styles, and the fact that they're naked.
** This happens most often to Eve. It might have something to do with her starting item...
** Lilith also tends to get this treatment in fanart. Given her long red hair and [[TheMinionMaster gameplay]] [[WeaponizedOffspring schtick]], it's probably not surprising.
** More bizarrely, there's a moderately popular depiction of [[spoiler:Delirium]] as a SlimeGirl.
* ThatOneAchievement:
** The NoDamageRun achievements. At least they're mercifully divided into groups, so you don't have to go through all eight in one run.
*** The king is the Dark Boy (Depths) NoDamageRun. That level set has just the right combination of pits, DemonicSpiders, GoddamnedBats, indestructible moving spike blocks, and cheap-as-hell bosses (plus Mom) to make it an absolute nightmare to get through, no matter how absurdly overpowered your character is. Even the Womb is easier because it does not have pits. ''Rebirth'' made the Womb somewhat more difficult by adding pits.
*** ''Rebirth'' ups the ante on that one with Dead Boy, achieved by completing one of the game's [[BrutalBonusLevel Brutal Bonus Level]]s, [[spoiler:The Chest or the Dark Room]], without taking damage. Here's hoping you packed a Holy Mantle... though it is slightly easier on [[spoiler:The Chest]], as four free (as long as you have keys) items are available from the starting room, and there's a chance to find more after completing every vicious room.
** ''Rebirth'' has [[spoiler:The Lost]]. Unlocking it is a massive GuideDangIt and a LuckBasedMission for the first part, though you can mercifully use seeds. Then, once actually unlocked, you have to do [[spoiler:no damage runs of the entire game through both {{Brutal Bonus Level}}s (Mega Satan is optional) and the boss rush]], and then do it all ''again'' on Hard mode to unlock [[spoiler:the Godhead]].
** Assembling Super Meat Boy and Bandage Girl in ''Rebirth''. In vanilla Isaac and WOTL, assembling Super Meat Boy wasn't too difficult to do as long as you got the Book of Revelations early enough. And you didn't have to assemble it to get the achievement, just kill all 4 of the Harbingers in one run. Unfortunately, the Book of Revelations no longer guarantees a Harbinger boss fight, instead giving a higher chance to run into them. The real kicker is that they now drop a Cube of Meat ''or'' a Ball of Bandages, so you have to hope the first one drops the item you want. Running into the Headless Horseman or Conquest will also ruin your chances of getting the achievements. Counter-intuitively, these achievements are actually easier if you go out of your way to avoid unlocking Conquest (which requires getting ten Angel Room items). Once Conquest is unlocked, it becomes downright impossible to manage a fair playthrough where you get the whole set. It's considered a lot less luck-based just to set up a way to infinitely recharge the Monster Manual to get a level 4 Meat Boy/Bandage Girl. It says something that these achievements have a lower completion rate than almost every other achievement in the game, second only to the shop unlocks and all of [[spoiler:the Lost's]] achievements. Mercifully, ''Afterbirth'' made this incredibly easy to earn with the addition of Greed mode and Lilith. Lilith's active item, Box of Friends, duplicates any familiars she has for the room it's used in. With Cube of Meat/Ball of Bandages, the effect is an immediate upgrade with each use. Greed mode's wave mechanic allows you to use the box at least three times in a row, since the charges accumulate with each wave. In tandem, this means you only need to find one of either item to get the associated achievements. Boss Rush or a 48 Hour Energy pill in the main game will also work. ''Afterbirth +'' went a step further and added the Potato Peeler, an-infinite use spacebar item which removes one red heart and generates one Cube of Meat along with a damage increase. Four hearts and you've got it.
** Collecting all of the items for Platinum God and Real Platinum God in ''Rebirth'' is far more annoying than in the original. This is mostly due to two reasons: the Secret Rooms and Steven. Secret Rooms have a much greater variety now, most of which do not contain items, which combined with a larger number of exclusive items means it is that much more difficult to get everything from that pool. Most resort to LoopholeAbuse with the D6, Judgement cards, and mushroom drops. Steven was originally a nightmare to find in ''Rebirth'' due to only being a rare boss drop, but ''Afterbirth'' has since fixed this by putting Steven back into the golden chest pool.
** Two achievements in Afterbirth+ depend on Daily Runs. 'Dedication' is for participating in, but not necessarily winning, 31 Daily Runs in a row, which is generally regarded as a month-long chore and impossible for those who don't have access to a computer every day for a month. 'The Marathon' is for winning 5 Daily Runs in a row, albeit they don't have to take place on consecutive days. Given that some Daily Runs task you with beating Mom with an easy character, and others require you to make it to Mega Satan with [[LethalJokeCharacter The Lost]], it's not uncommon to find threads on the Steam forum warning users to stay away from a particularly bad daily. A multitude of threads popped up on January 29th when the Daily Run included ''no damage-up items at all'', yet still required players to beat [[TrueFinalBoss Mega Satan]] with [[MagikarpPower Lilith]]. To make things worse, while they only unlock a trinket and a pill, both of these are necessary to unlock the [[HundredPercentCompletion 1000000% completion]] achievement, meaning that you could have beaten every challenge and every boss with every character, but if you can't take part in 31 Daily Runs in a row, you'll never unlock [[LastLousyPoint the final achievement]] in the game. Thankfully, a later patch made it so that the 31 Daily Runs didn't need to be consecutive, removing Dedication from this territory.
* ThatOneAttack:
** Mom's hand during the Mom boss battle, not to be confused with the Mom's hand monster in ''Rebirth''. It comes out to swat you if you hang around the doors too much, and is near-instantaneous. It's avoidable, but you probably won't manage to do it on purpose. Playing as [[spoiler:The Lost]]? Game over.
** The Bloat's brimstone attack, which once again has no tell and hits almost instantaneously. And he'll use it without fail if you get in range while he's not using another attack.
** The Adversary's Brimstone attack. It's telegraphed by a unique roar, but that's of little comfort when the beam ''actively curves to hit you''. While it is possible to dodge by getting close and circling the boss, this attack becomes a terror when two Adversaries are in a single room and the one in the other corner unleashes the beam.
** Mega Fatty, an otherwise easy to dodge if [[DamageSpongeBoss spongy boss]], has one really annoying attack. He can, with almost no warning, leap from his current position to where you're standing in less than a second, which is practically undodgeable if you're standing still.
** Brimstone beams are That One Attack for the game as a whole. They have no travel time, cross the entire room, pass through all forms of cover, and linger for a couple of seconds. Fighting multiple enemies with Brimstone attacks in a room generally means you run out of room to dodge very quickly.
*** Of course, when ''you'' have them they have the same advantages as the boss ones and items like the Head of Krampus, Tammy's Head (if you have brimstone), and especially [[spoiler:Mega Blast]] can deal a lot of damage with their beams. Tammy's Head is stronger with Brimstone than the Head of Krampus because it shoots in all directions instead of the cardinal directions and recharges after a single room. This is all if you can get the items in the first place (Azazel at least benefits more from Tammy's head, see below in "Tier Induced Scrappy").
** [[spoiler:Hush's]] Continuum attack, where his bullets wrap around the screen. Several factors make this attack more difficult to avoid than it sounds on paper. First, the bullets move ''faster'' the longer they stay in the air, and by the time they finish their wrap around will be moving extremely fast. Second, he sprays the bullets in an expanding cone, so they become a large wall when they return from the other side. Third, the bullets wobble as they travel, making predicting their patterns and finding a safe spot difficult. Fourth, he can suddenly switch directions and unleash a new bullet spray before the old one is done, overlapping them and making dodging nearly impossible. Finally, even if you do manage to figure out where the safe spots are, the boss can fire from any number of positions, forcing you to figure out the new safe spot on the fly.
* ThatOneBoss: [[ThatOneBoss/TheBindingOfIsaac There's enough to have its own page]].
* ThatOneLevel:
** The Cellar can be a much harder starting point than The Basement, usually involving harder enemies and rooms with a borderline fetish for spider enemies. In addition these levels can frequently stick you facing either [[ThatOneBoss The Widow or The Haunt]] as your first boss battle of the run.
** Necropolis. Not only is it home to quite a few DemonicSpiders (such as Hangars and Masks + Hearts) and numerous spike traps, but it also holds some ''very'' annoying bosses like The Bloat and The Mask of Infamy. Fortunately, the latter only applies for Necropolis 1, as Necropolis 2 always has [[DiscOneFinalBoss Mom]] as the floor's boss. There's still the risk of them spawning in Boss Challenge rooms, though.
** The [[spoiler:Dark Room]], when compared to fellow BrutalBonusLevel The [[spoiler:Chest]]. While the four initial chests in the latter all contain items, the ones in the former are red chests with the usual fare, meaning that there is no guarantee of getting anything that helps you survive the level. Additionally, the [[spoiler:Dark Room]] tends to contain more dangerous enemies than The [[spoiler:Chest]], including the likes of multiple Fallens or even Mask of Infamy.
** The Womb on Greedier Mode. Four waves spawn with less than a second of delay. If you aren't overpowered by now or have health to spare, you're dead, no question.
* ThatOneSidequest: Most of the challenges, especially the ones included in ''Afterbirth'', qualify as this. Notable offenders include:
** The Suicide King challenge in ''Rebirth''. Have fun playing the entire game with exploding tears that boomerang right back in your face!
** The Family Man challenge is probably the the hardest of the base game. You're blindfolded, and your only means of damage are through three familiars. Thankfully, one of them is Rotten Baby, which scales with your damage, but other than that, you're gonna have a very hard time trying to damage enemies even a little bit. It's borderline impossible to complete the challenge without resorting to resetting until you can get a Cube of Meat or Ball of Bandages on the first floor.
** The Speed! challenge in ''Afterbirth''. Enemy movement and bullet speed are dialed up significantly while you start as basic Isaac. There's Treasure Rooms, but that's little comfort when bosses like Gurdy Jr. can move twice as fast and become practically unavoidable. Oh, and if you don't finish all the way to It Lives in under 16 minutes, you get half a heart of damage ''every few seconds'' '''which can kill you!''' [[https://www.youtube.com/watch?v=dpBvYb60ehw It goes to the point it's almost impossible to even beat the first floor if you get a hard boss unless you get a good start]]. It's basically saying "reload until you get Brimstone or something else that kill instantly, otherwise you lose." A patch eventually increased Isaac's movement speed as well, making the challenge ''slightly'' more manageable in that you'll at least be able to outrun most enemies that chase you.
** The Brains! challenge, again in ''Afterbirth''. You're not only blindfolded, but your only offensive weapons are three Bob's Brains, which is a ScrappyWeapon infamous for its tendency to blow up right in your face. What makes this worse is that you're playing as [[spoiler:???/Blue Baby]], making it more difficult to recover health, and you have to fight all the way to the Chest.
** The Guardian challenge, once again in ''Afterbirth''. You must protect Isaac's Heart which isn't following you, but rather the Punching Bag that wanders around the room. Oh, and the Punching Bag is the one that takes damage, not the heart. You have no real control over whether or not you take damage, as all enemies attack the Punching Bag rather than you. Hazards like red poop and spikes turn the challenge into a LuckBasedMission due to the fact that, if the Punching Bag touches a hazard just once, you lose a ''lot'' of hearts instantly!
** Most challenges where you're blindfolded and thus unable to fire tears falls into this category, such as "Cat Got Your Tongue" (rely only on flies and Guppy's Hairball for damage) and Solar System (orbitals only).
** The Ultra Hard challenge in ''Afterbirth+'' lives up to its name. You are Isaac (minus the D6) stuck with Curse of the Lost, Curse of the Maze, Curse of the Blind, and Curse of the Labyrinth with the possibility of additional curses on top of those. The four permanent curses furthermore ''cannot'' be dispelled with the Black Candle or Dagaz Rune. All enemies and bosses that have Champion variants will be Champions, no exceptions. What's worse is that the challenge will never drop hearts - ever. The only way to get health is to get HP Ups, items that directly give you health (items that drop hearts on the ground do not work), or get a regenerating item ala Placenta or Blood Leech. What's worse is that the end goal is beating Mega Satan, which sets up a long and frustrating road, ''and'' the Ehwaz Rune doesn't work, so you can't skip any floors either. Oh, and your reward for all that effort? Samson starts with the Child's Heart trinket. A trinket you'll almost certainly discard because it will replace other, more useful drops like keys.
* TierInducedScrappy:
** Samson in the original game. To put this into account, he's more despised than the game's resident ([[LethalJokeCharacter Lethal]]) JokeCharacter. He starts with a meager one heart container and crappy damage output, and while his starting item increases his damage for killing enemies, it's useless against roughly half the bosses in the game since the boost resets every time you enter a new room. In other words, anything Samson does, Judas can do better.
** Eve, too, to a lesser extent. She starts the game with below average health and damage, and her initial abilities are all essentially CastFromHitPoints. Do the math. It's so bad that, before the DLC, the LethalJokeCharacter actually had a higher completion rate, despite being more joke than lethal.
** [[RescuedFromTheScrappyHeap Rebirth gives both of these characters buffs.]] Samson now starts with three hearts and his damage stacks don't reset until he leaves the floor. Eve's Whore of Babylon will trigger at a full heart instead of half a heart (it still triggers at half a heart for everyone else). Cain, however, was hit hard with the nerfbat, as his Lucky Foot no longer recycles bad pills. ''Afterbirth'' eventually buffed Cain by starting him out with the Paperclip, provided it is unlocked.
** Azazel is often frowned upon for being largely unbalanced compared to the other characters. To explain, he starts with three black hearts (but can acquire regular health through powerups), flight, and a short-range Brimstone attack. The range issue is at best minor, and Azazel can clear rooms like nobody's business. With a little skill, Azazel can easily make it all the way to Mom in time for the Boss Rush without any significant powerups. With powerups, he's a murder machine. He eventually got nerfed in ''Afterbirth'' by having his fire rate lowered, but this can easily be undone with a couple Tears Up items.
** How about [[spoiler:The Lost]]? He can fly, but he's a OneHitPointWonder and doesn't even start with any items besides one measly coin. The fact that one of his item unlocks requires you to beat every final boss (save for [[spoiler:Mega Satan]]) on ''hard'' certainly does not help matters. Fortunately, as AuthorsSavingThrow mentions above, he eventually got the buff he deserved.
** Lazarus has negative luck and short range but starts with a pill and the ability to resurrect with 1 heart; problem is, the pill can randomly screw you and the resurrection isn't something you should rely on the first place. So, when compared to the other characters, Lazarus is generally considered to be the most boring.
** By getting 1000 coins in the Greed mode donation machine, [[spoiler:you unlock The Keeper (which is basically a playable shopkeeper). Instead of hearts, he has two coin slots; any kind of damage takes one coin, but taking another coin on the floor heals it back; all hearts are converted into blue flies. Only one item in ''Afterbirth +'' has the ability to increase his health (up to 6), and you can decrease it with items or Devil Deals that take away a heart. This means virtually all health increasing items are worthless unless you've lost one coin slot already. Two heart deals are instant death without some sort of revive. Furthermore, coin damage counts as red heart damage as far as Devil/Angel Rooms are concerned, so without the Goat Head you can never take damage if you want access to them. He gets a triple shot to start, but the tear speed is abysmal and you'll be begging for tear increasing items. On the plus side, if you find a Swallowed Penny or the less reliable Piggy Bank (it is programmed to drop less coins than normal on Keeper), you're essentially immortal as long as you have two coin slots. Even his starting items are at best mundane. He begins with a single bomb, and through unlocks can have the Wooden Nickel, a single coin, and the Store Key trinket to unlock shops. The items he unlocks are at best situational, with the Rib of Greed being the only moderately useful one. In short, Keeper has a mountain of setbacks, but no advantage that makes up for the shocking difficulty.]]
* WereStillRelevantDammit: One of the items in ''Afterbirth +'' is [[VideoGame/PokemonGo Poke Go]]. By the time the expansion was released, while it still has a regular player base, is largely regarded as a fad of 2016 by most people.
* TheWoobie:
** Isaac. What this poor kid goes through, no human should ever go. And yet, [[IronWoobie he takes it all like a badass]]. A [[TearsOfFear weeping]], [[FullFrontalAssault naked]], [[FearTropes terrified]], prepubescent badass.
*** If you thought Isaac was a Woobie before, the DownerEnding multiplies it by tenfold. [[spoiler:As it turns out, he is indeed slowly asphyxiating to death within a chest.]] We are finally given the reason why: [[spoiler:[[DrivenToSuicide He did it to himself]]. After losing his sister and pets and watching his father walk out on his mother, he demonizes himself and blames everything that happened on him. The entire game is a DyingDream as he [[SanitySlippage goes insane]] and slowly suffocates to death]].
** Mulligans and Hives are weak, sobbing enemies who do not attack Isaac, and who are [[BodyHorror slowly being turned into living flies' nests]]. Or [[AndIMustScream undead, but still suffering, flies' nests.]]
*** The lowest level Mulligans don't even try to attack you, instead running away when you approach and cowering in the corner.
*** WOTL adds a power up that turns you into one. It's every bit as useful as it is horrifying.
** The true ending of the game not only ups Isaac's own Woobieness, but also does the same for [[spoiler:his mother]]. Not only does [[spoiler:she have to go through losing her daughter, and having her husband leave her]], but [[spoiler:she finds the little skeleton of Isaac, who had long been DrivenToSuicide]]. Also possibly a JerkassWoobie [[spoiler:assuming that the abuse implications in the items is still true and that Isaac's mother was the abuser.]]
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