Trivia / The Binding of Isaac

The following tropes have their own pages:

• Author's Saving Throw
• Urban Legend Of Zelda
• What Could Have Been

---

• Ascended Fanfic: The Repentance expansion brings over the entirety of the Antibirth Game Mod, with some tweaks (notably a new soundtrack which replaces Mudeth's original work^note Though that is still accessible through modding, and Mudeth even made some new tracks for the Afterbirth content) applied to keep it consistent with the rest of the game.
• Ascended Fanon:
  • The "Muliboom" name for the kamikaze Action Bomb variety of the Mulligan was a Fan Nickname for a while before being made official.
  • Ur-Gurdy is a fictitious boss that spawned an Urban Legend of Zelda in Rebirth. She was added as "The Witness" in Antibirth (now renamed Mother), and serves as the Disc-One Final Boss of Repentance. Funny enough, what started as an Urban Legend of Zelda ended up becoming official.
    • According to this post, Mother started as a joke by Reddit user varkarrus.
  • In addition to Mother, The Visage and Reap Creap are taken directly from some of NotYourSagittarius's mock-ups prior to working on Afterbirth.
  • Eye of the Occult and Dream Catcher originated from this reddit post.
  • The alternate versions of player characters unlockable in the Repentance DLC were originally known as "B-sides" officially, after a similar mechanic from Nuclear Throne. Fans instead dubbed them "Tainted" characters, after the mutated Boss in Mook Clothing versions of certain enemies encountered during the Ascent. Later update logs for the DLC use this name for them.
• Ascended Glitch:
  • In the original game, it was possible, with clever usage of the D6 and items that reduce its charge rate, to completely exhaust all "pools" the game could pull items from. If another item is produced when the pools are empty, the game would freak out and create an "Undefined" item, with a sprite that scrolls through almost every item sprite in the game and does nothing upon pick-up. Making a second Undefined show up would then crash the game. Come Rebirth, one of the new activated items that can be unlocked is "Undefined", which has a sprite made up of parts of other item sprites and displays the same details the original item did when picked up. Item pools are still exhaustible in Rebirth (and, as a possible nod to the original glitch, the Undefined item is one of the easiest ways to do it), but it only results in a generic Heart Container item. In Afterbirth+, an achievement was added called "U Broke It!", which rewards the player for exploiting these tricks and receiving 50 items in a single run, which would normally be impossible.
  • The "Buttless Chub" glitch; one of the possible Womb rooms of the original game contained two Larry Jrs. and a Chub. Thanks to the limitations of the game, the Chub spawned without her third segment, leaving her unable to spawn maggots from it. The room still exists in Rebirth, and Chub is still missing her behind despite the new engine being able to handle it.
  • The Polaroid was a trinket that let you access The Very Definitely Final Dungeon in the Wrath of the Lamb expansion. Originally it was supposed to have a very low drop rate from Mom, but it was accidentally made to drop 100% of the time on release. Rather than patch it out, the devs let it be since the final area was no longer a secret. Come Rebirth, and it's now a passive item so it doesn't take up your trinket slot, and even has a new Evil Counterpart you can take instead.
  • One trinket, the Liberty Cap, was glitched so that it sometimes gave the effect of the Compass item (which would reveal all special rooms on a floor) for a single room, rather than act as a random mushroom item. This effect carried over to Rebirth. Strangely enough however, the effect was later removed in Repentance, with the patch notes stating the trinket was "fixed", as if it were still a glitch.
  • Isaac's weird hitbox allowed him to walk diagonally in-between spikes and avoid taking damage from them in the original game. This is still possible in Rebirth, but it requires more precision. It was also made an explicate feature of some Devil and Curse rooms, which require you to walk between spikes to pick up items.
  • Getting revived by Lazarus's Rags as Tainted Forgotten has Lazarus Risen appear as a pile of bones with Lazarus' head stacked on top of it, but otherwise functioning normally. This was originally a bug during development, but Kilburn found it funny enough to keep it in for the patch release.
  • For a short while, using the item Suplex just as Berserk was about to wear off with frame-perfect timing would instantly kill whatever you Suplexed, including Final Bosses. While this was patched out, pulling the trick off now will cause a massive explosion that deals tonnes of extra damage.
  • For whatever reason, in Patch 17.9 Baby Plum started using the joke death animation caused by the Easter Egg item G FUEL!, where a realistic missile is dropped on her and causes a poorly-cropped explosion, in normal runs. Instead of removing it completely, the following hotfix patch reduced the chance of this animation playing to 0.0001%.
• Ascended Meme:
  • The Rebirth is Cancelled joke that Northernlion and his friends started can be one of the messages that you get from fortune tellers. A bit ironic, since NL discredited the meme because those who couldn't read the sarcasm started giving the devs shit over it.
  • The Bloat is one of the most hated bosses in the game, to the point of having a subreddit dedicated to hating him. In the April's Fool challenge added in Afterbirth+, every single boss is replaced with him, with the only way to get rid of him for a floor is to have your active item act as the Book of Revelations, which still overrides the boss with a Horseman.
  • The popularity of Ultra Greed's ample rear has become immortalized with an official mousepad from Nicalis and later as a card in the Requiem expansion of the Four Souls card game.
  • While not within the game itself, the Requiem expansion of the Four Souls card game makes reference to both "The Isaac of Isaac: Reisaac" and the infamous "You little F**ker" rant, among others.
• Based on a Dream: According to a Discord AMA from Kilburn, the Red Key item was originally based on a recurring dream of his where he would find doors that weren't normally there in real life, and wake up before he could open them. Edmund encouraged him to connect it with the Tainted characters.
• Christmas Rushed: Despite the generally high quality of Repentance, it's obvious that it wasn't quite finished in time for release. Almost all of the Tainted characters unlocked at least one functionless item, as did Lilith. Half of the characters had no effect for Birthright, an item that's supposed to do something different for everyone. There are a few items that made The Beast nearly impossible due to wonky physics. Tainted Lazarus was quite literally unfinished according to Word of God, and was released in an unplayably weak state. All of this was to avoid the DLC entering Development Hell, since it was already pushed back several years by the time it came out. All of this was eventually fixed in a massive patch in November of 2021.
• Creator Backlash:
  • Edmund was reportedly pretty disappointed at how the Lost was discovered. Not because it was found quickly, but because people found it by datamining the game, rather than the community figuring out the cryptic hints in-game piece by piece. With the later Afterbirth expansion, Edmund countered this by patching in secret material when the community solved the puzzle: it wasn't even present in the game code until it was unlocked!
  • invoked During an interview with Northernlion, Edmund revealed that the only reason Repentance is such a massive Difficulty Spike compared to the base game and Afterbirth/Afterbirth+ is because he wasn't happy with players and streamers breaking the game.
  • After the Mewgenics page went live on Steam, Edmund did a comparison post between Isaac and his next game. In the same post he expressed regrets over the lack of item descriptions in Isaac. While he was fine with it at first, he would later hate the decision as the item pool grew over the years, forcing players to play the game alongside a browser or with the help of mods.
• Creator's Favorite:
  • In an interview with Northernlion in 2012, Edmund McMillen said that Eve was his favourite character.
  • According to this Tweet, The Forgotten is Edmund's current favourite. Then again, given that it was posted only a few months after the fourth Booster Pack was released, it's probably him being a Trolling Creator.
• Dummied Out:
  • The "Oh No!" / Explosive Diarrhea pill is probably one of the few unintentional examples, disappearing from the game sometime around the Wrath of the Lamb update. The pill returned not only in a patch to the original game, but also in Rebirth.
  • As hinted here, Triachnid was originally cut before the game was released. It wasn't removed entirely, though. Due to a glitch, it originally would replace the Cathedral's True Final Boss. This was eventually corrected, and Triachnid was added in as a normal boss.
  • Afterbirth has an unused boss known as "Skinless Hush", implied to be an alternative form of an existing boss. Both the boss' code and spritesheet are in the game's files, but the spritesheet has only one finished sprite and, if forced to spawn in-game, the boss has absolutely no AI attached to it. Edmund claimed it was a Red Herring for data miners, although Tyrone later posted concept art showing it was at least at one point intended to be used in game. Edmund later confirmed that Skinless Hush was not a red herring.
  • There are three unused bosses in Repentance that were cut for time. Cadavra, a dual-boss of sorts that only exists as two sprites (never finished despite being revealed in a Twitter tease); Raglich, a posthumous Ragman/Rag Mega that can be summoned with the debug console and is mostly functional; and Clutch, a seemingly finished boss with an intro screen and everything that's a King Mook to the new resurrecting skeleton enemies. A more polished Clutch would later be properly added in patch 1.7.8 as a boss in the Ashpit.
• Feelies: The Nintendo Switch boxed release includes a fully illustrated instruction manual, which parodies the original Legend of Zelda game manual, as well as some stickers featuring some of the game's characters and enemies.
• Follow the Leader: The success of The Binding of Isaac has led to a slew of other roguelike games imitating its basic gameplay style.^note The qualities of games following the Isaac formula tend to include the following points: top-down twin-stick shooters that have generally fast-paced gameplay; multiple rooms to explore spread over several randomly-generated floors in a dungeon crawler-like format; require all enemies in a room to be defeated in order to progress; allow an extremely limited degree of backtracking to pick up passed-over items or explore other paths (you can freely travel between rooms on a floor, but progressing from one floor to the next is a one-way trip); tend to become Bullet Hell in their later stages if they don't qualify from the very start (especially during boss fights); usually have the player and the enemies follow wildly different rules in terms of durability (with the player's health typically being defined more-or-less as "number of hits until death", while enemies have larger HP numbers that allow player attacks to deal wildly varying amounts of damage based on their build); feature a wide variety of (randomly-placed) collectible items to adjust the player character's stats and fighting style mid-run; have strong macrogame elements where additional items, characters, and levels are unlocked through multiple playthroughs and achieving various objectives (with the definitive Final Boss usually not being available on the first (or even second, third, or fourth) playthrough); often have some in-universe explanation for why death is not permanent and why death and success alike send the Player Character back to the start of the journey — sans most if not all of the items and upgrades they acquired during the run (such as some form of Tricked Out Time, a hilariously-large supply of interchangeable would-be heroes, or the events of the gameplay taking place in a Mental World and having a loose-at-best connection to in-universe reality); and often have some late-game twist that turns the initially-presented plot on its head (to varying degrees) which may or may not tie into the reason why death isn't permanent. Some of these points are flexible and can be bent or even disregarded, but others need to be followed nearly to the letter to qualify a game as an "Isaac-like". Derivative games include Nuclear Throne, Enter the Gungeon, Our Darker Purpose, Monolith, Soul Knight, and Undermine, among others.^note To go over some of the hand-waves for multiple playthroughs: Nuclear Throne and Enter the Gungeon use Tricked Out Time, Undermine uses We Have Reserves, and Our Darker Purpose and The Binding of Isaac itself use the "story is not connected to gameplay" Mental World approach. It's gotten to the point where some people, most notably Northernlion, have proposed referring to these games as "Isaac-likes"^note specifically, Northernlion said that in the description of his review for Our Darker Purpose, which was released in 2014.
• Hey, It's That Sound!: The sound effect for picking up coins in Rebirth is practically identical to the sound effect for picking up gold in Spelunky.
• In Memoriam: Satoru Iwata's birthday is December 6th, 1959. On December 6th, 2015, there was a special Iwata-themed daily challenge, complete with custom character graphics.◊
• Orphaned Reference:
  • Lil Dumpy debuted in Antibirth as a friendly version of the Dumpling enemies that the mod also added. When Antibirth was officially ported into the main game, Lil Dumpy was added, but the Dumpling enemies were cut, leaving the reference stranded.
  • Antibirth added an item called Jacob's Ladder, a reference to the Biblical story of Jacob seeing a ladder that leads to Heaven. However, Afterbirth+ already had an item called Jacob's Ladder, based on the electric phenomenon. The Antibirth one was renamed The Stairway when it was ported, but the sprite is still obviously a ladder and it's still unlocked by playing as Jacob & Esau.
• The Other Darrin:
  • Patty Allen-Scott voiced Mom's lines in the original Flash release, but for Rebirth and all following expansions her role was recast with Carla Kihlstedt.
  • As noted under Real-Life Relative, Isaac's voice actress in Rebirth Tallulah Rossi was replaced with her brother Viggo for Repentance as Tallulah's voice had by that time aged out of the child range.
• Promoted Fanboy:
  • Spider, the mind behind the SpiderMod program (a modified version of Isaac that runs in a separate .exe, is more optimized, and adds a number of features, including various cheats and controller support), was hired to do coding work for the remake. Afterbirth then introduced an item named Spider Mod, giving all enemies individual health bars and showing how much damage your tears do to them, which was one of the functions introduced by SpiderMod.
  • NotYourSagittarius, creator of the Basilica, Topheth, and a few boss concepts, was hired to work on the Afterbirth expansion.
  • Missing HUD, a popular mod for Afterbirth that gives you a more complete breakdown on your stats (including your devil deal and angel room chances), was made into an official feature in Afterbirth+, called Found HUD in the options.
• Real-Life Relative: The voices of Isaac's family in Rebirth are done by a real-life family: Carla Kihlstedt as Mom, her husband Matthias Rossi as Dad, and their daughter Tallulah as Isaac who was later replaced by her younger brother Viggo for Repentance.
• Sleeper Hit: Word of God has stated he never expected Isaac to be so popular. At one point he considered giving it away because he didn't believe anyone would actually want to spend money on something so weird and dark.
• Throw It In!:
  • When an item pool is depleted in Rebirth, all future items from that pool are replaced with Breakfast, a standard HP up. This was apparently a bug, but ended up being the perfect solution to empty item pools compared to what happened in the Flash version. Given that Sacrificial Altar^*which ignores pool rules and always spawns Devil items has its own special version of Breakfast with The Pentagram, it's safe to say this is now an intended feature.
  • As Afterbirth+’s secret character, you can spend the last of your health on a Devil Deal as The Soul, then switch to The Forgotten before you die. Although The Soul still dies, the run will continue and you are locked as The Forgotten until you get more soul hearts, at which point The Soul comes back. This was caught in playtesting, but kept as it was felt "thematically appropriate".
• Torch the Franchise and Run: Rebirth does this with the Repentence DLC. After seemingly every single expansion making Isaac's story worse, Repentence adds one more True Final Boss. Beat it, and Isaac, free of all his self-hatred and sins, lets go of the mortal coil and ascends to Heaven. There's simply nowhere more for the story to go, and understandably the creators have stated it's the last DLC.
• Uncredited Role: Carla Kihlstedt as the voice for Mom, as well as the violin composer for a few tracks. She finally receives a small credit as a special guest in Repentance's OST.
• Word of Gay: Out of all characters, Edmund has stated that The Rainmaker is gay, making him the only monster thus far to have an explicit sexuality.
• Word of God: Some information can be gleaned from McMillen's Tumblr blog and (now defunct) Formspring, though also be prepared for a fair bit of Teasing Creator.
  • For the longest time, it was believed that Isaac used to have a sister who either left or died, but Word of God has confirmed it not to be the case.
  • Edmund has revealed that Isaac is Steven, thus making TBOI the prequel to TIME FCUK. Although, this piece of trivia should be taken with a grain of salt, since Edmund is known to be a tease. It most likely has more to do with said games sharing similar themes in the narrative, with Isaac and Steven choosing to go into their boxes, but only Steven choosing to come out.
  • With Edmund's guest appearance in a Roundtable stream, he confirmed that the game's narrator, who voices the introduction and occasionally calls out pills/cards, is supposed to be Isaac's dad (or at least a hallucination of him). This would later be more-explicitly confirmed in the final endings of The Legend of Bum-bo and Repentance.
• Working Title: Two. First Love Sick, then Mom. The Binding of Isaac itself was thought of as a play on The Legend of Zelda.

---