- By pressing "Tab" on the challenges portion of the main menu, you can access custom challenges added by mods. The Racing+ mod uses custom challenges to facilitate multi-character speedruns where you must beat the game multiple times in a row on various characters.
- These custom challenges will automatically take you to the next character so that you never have to return to the menu. They will also show a timer on the screen and your current character progress.
- You can restart with the current character by tapping R. You can go back to the first character by holding R.
- On floors 2 and beyond, you can double-tap R to restart with the current character.
- In all seasons, the first character will get More Options. After the Treasure Room is entered, More Options will be removed. (This is to speed up the process of finding an item and getting a run going.)
- In all seasons, both The Polaroid and The Negative will spawn after defeating Mom. Neither are required to travel to The Chest / the Dark Room. (This is to increase strategy and decision making.)
- In all seasons, on the first character, Devil Rooms and Angel Rooms will have nothing in them if you teleport to one from a Curse Room on the first floor. (This prevents resetting for a Devil Room item.)
- In all seasons that go to the Dark Room, We Need to Go Deeper will not work on Womb 2.
- In all seasons that go to the Dark Room, the spikes in a Sacrifice Room will never take you to the Dark Room.
- You must defeat Blue Baby on the following 7 characters:
- 0 - Isaac
- 3 - Judas
- 7 - Azazel
- 10 - The Lost
- 12 - Keeper
- 13 - Apollyon
- 15 - Bethany
- For each character, you can choose to play as either the normal version or the tainted version.
- Bethany & Tainted Bethany start with Duality in addition to their other items.
- You must complete the game with the following 7 characters:
- 2 - Cain
- 5 - Eve
- 12 - Dark Judas
- 16 - The Forgotten
- 21 - Tainted Isaac (with Birthright)
- 27 - Tainted Samson
- 28 - Tainted Azazel
- All characters start with the Compass.
- Tainted Isaac starts with Birthright.
- The 1st, 3rd, 5th, and 7th runs will go to The Chest.
- The 2nd, 4th, and 6th runs will go to the Dark Room.
- You are randomly assigned a character at the beginning of the run. (You cannot choose the order of the characters.)
- You are randomly assigned a build at the beginning of the run.
- Resetting the game will change the seed, but not change the randomly assigned character or build.
- The randomly selected character & build for the first character will expire after 1.5 minutes or when a Basement 2 boss dies, whichever happens first.
- Instead of choosing a character order, players must ban 3 builds.
- When resetting on the first character, you will never be given the same character or build twice in a row.
- Duplicate starting builds will never be given over the course of a 7 character run.
- The custom death mechanic from seeded races is applied.
The randomly assigned starting builds are as follows:
- 0 - Cricket's Head (#4)
- 1 - Ipecac (#149)
- 2 - Magic Mushroom (#12)
- 3 - Polyphemus (#169)
- 4 - Proptosis (#261)
- 5 - Brimstone (#118)
- 6 - Maw of the Void (#399)
- 7 - Crown of Light (#415)
- 8 - Godhead (#331)
- 9 - Sacred Heart (#182)
- 10 - Revelation (w/ no soul hearts & no flight) (#643)
- 11 - 20/20 (#245) + The Inner Eye (#2)
- 12 - C Section (#678) + Steven (#50)
- 13 - Chocolate Milk (#69) + Steven (#50)
- 14 - Cricket's Body (#224) + Steven (#50)
- 15 - Dead Eye (#373) + Jesus Juice (#197)
- 16 - Death's Touch (#237) + Sad Onion (#1)
- 17 - Fire Mind (#257) + 13 Luck
- 18 - Haemolacria (#531) + Sad Onion (#1)
- 19 - Incubus (#360) + Twisted Pair (#698) + Forgotten Lullaby
- 20 - Monstro's Lung (#229) + Sad Onion (#1)
- 21 - Tech X (#395) + Lazy Worm
- 22 - Tech.5 (#244) + Jesus Juice (#197)
- 23 - Technology (#68) + A Lump of Coal (#132)
- 24 - Pointy Rib (#544) + Eve's Mascara (#310)
The Forgotten is guaranteed to get one of the following builds:
- Magic Mushroom
- Chocolate Milk + Stephen
- Ipecac
- Polyphemus
- Sacred Heart
- Proptosis
- Haemolacria + Sad Onion
- Pointy Rib + Eve's Mascara
- C Section
Some builds are banned on certain characters:
- 5 - Eve
- Crown of Light
- 27 - Tainted Samson
- Ipecac
- Brimstone
- 28 - Tainted Azazel
- Polyphemus
- Godhead
- Revelation
- Cricket's Body + Steven
- Dead Eye + Jesus Juice
- Death's Touch + Sad Onion
- Fire Mind + 13 Luck
- Haemolacria + Sad Onion
- Pointy Rib + Eve's Mascara
- Tech X + Lazy Worm
- Sol is removed from the Planetarium pool. (It is useless since the player starts with The Compass.)
- Cain's Eye is removed from the trinket pool. (It is useless since the player starts with The Compass.)
- Not entering a Treasure Room no longer increases the chance of a Planetarium appearing. (This is to make the season consistent with seeded races.)
- The Treasure Room on the first floor is removed.
- On the first character, the following room types are removed on the first floor:
- Miniboss Rooms
- Curse Rooms
- Libraries
- Planetariums
- You must complete the game with the following 7 characters:
- 3 - Judas
- 4 - Blue Baby
- 6 - Samson
- 8 - Lazarus
- 24 - Tainted Judas
- 26 - Tainted Eve
- 37 - Tainted Jacob
- Blue Baby and Tainted Judas start with Birthright.
- You are randomly assigned a character at the beginning of the run. (You cannot choose the order of the characters.)
- You are randomly assigned five starting items at the beginning of the run, similar to how diversity races work.
- All of the other changes from diversity races are also present.
- Additionally, the following items can never be randomly assigned, since they are too powerful:
- The 27 starting items (as per the "seeded starts")
- 147 - Notched Axe
- 158 - Crystal Ball
- 311 - Judas' Shadow
- 324 - Undefined
- 333 - The Mind
- 592 - Terra
- 628 - Death Certificate
- 660 - Card Reading
- 689 - Glitched Crown
- The following items are removed from pools, in addition to the ones that are normally removed from diversity races (like D4):
- 84 - We Need to Go Deeper!
- 441 - Mega Blast
- 625 - Mega Mush
- You must complete the following 7 goals:
- Blue Baby
- The Lamb
- Mega Satan
- Boss Rush
- Hush
- Mother
- Dogma (without The Beast fight)
- You can only complete the Mega Satan goal on the second character and beyond. Except for that, you can do the goals in any order that you like.
- Some goals are altered:
- Mega Satan - The key pieces are not required.
- Hush - The Blue Baby phase of the fight will be automatically skipped.
- Mother - The door to Downpour/Dross will appear on the second floor and will be automatically unlocked.
- Dogma - Will appear in place of Dad's Note.
- You cannot warp to Home from Basement 1 by using the Glowing Hour Glass.
- You must complete the game with the following 7 characters:
- 0 - Isaac
- 3 - Judas
- 7 - Azazel
- 10 - The Lost
- 13 - Lilith
- 18 - Bethany
- 22 - Tainted Magdalene
- Lilith starts with Birthright.
- Bethany starts with Duality.
- Tainted Magdalene starts with Steven and Birthright.
- If you transform into a different character mid-way through the run, all of the starting items granted to the old character will be removed.
- The 1st, 3rd, 5th, and 7th runs will go to The Chest.
- The 2nd, 4th, and 6th runs will go to the Dark Room.
- When holding a collectible above your head, you can hold down a button to activate a "storage" mechanic.
- When a collectible is stored, it will not be granted to the player, but will go into storage instead.
- All stored collectibles will appear in the starting room of the next character in the speedrun.
- If you do not take a stored collectible in the starting room, it will continue to be stored for future characters.
- You can only store an active collectible on the initial pickup. (In other words, if you have already touched the active collectible on the current run, then you cannot store it.)
- Stored collectibles are removed from pools when you store them (even though they do not go into your inventory).
- Stored collectibles are not removed from pools if they appear in the starting room of the run (but they are removed if you take them).
- Stored collectibles cannot be rolled, voided, duplicated, or moved (with e.g. D6, D100, Eternal D6, Spindown Dice, Void, Abyss, Diplopia, Crooked Penny, Moving Box, or Dice Shard).
- If you reset or die before touching the checkpoint/trophy, any collectibles that you stored on the run will be lost. Items already stored from previous characters will remain. (This prevents you from storing items from the Basement 1 Treasure Room.)
- You cannot re-store items that are spawned in the starting room.
- The following items are removed from all pools:
- 84 - We Need to Go Deeper
- 622 - Genesis
- The following cards are removed on the first character:
- Wild Card
- ? Card
- You must complete the game 7 times using the Babies Mod, which provides a different random baby with a unique ability on each floor.
- The 1st, 3rd, 5th, and 7th runs will go to The Chest.
- The 2nd, 4th, and 6th runs will go to the Dark Room.
- The "instant starting item" mechanic from season 2 also applies to this season.
- The builds are the same builds as in season 2.
- Unlike season 2, there are no build vetos.
- If you want to do a multiplayer race of one of the above seasons, then you can create a race with a format of "Custom" and a race goal of "Custom".