Seeds

Seeds, essentially random strings of characters, are used as the basis for all decision making in the game. By inputting a seed manually, you can guarantee that most randomly-generated decisions will occur the same every time. For instance, two players using the same seed will find the same items in the same locations.

Inputting any seed, even a special seed, causes the 'no trophies' mark to appear, meaning that achievements can't obtained from that run. Special seeds appear to not actually guarantee that you get a specific layout.

All alphanumeric characters are accepted except for I, O, U, and V.

Special Seeds

The following seeds will apply a certain effect to your game.

Seed	Effect
BASE MENT	Basement repeats infinitely. Due to the internal workings of the game, once the entire item pool is exhausted only the item Breakfast will continue to spawn.
BLOO OODY	Makes a lot more blood appear after death of the enemies.
CAMO K1DD	Turns character invisible.
CAMO DROP	Like CAM0 K1DD but pick-ups are invisible instead.
CAM0 F0ES	Like CAM0 K1DD but enemies are invisible instead.
COCK FGHT	Makes all enemies charmed permanently.
CHAM P10N	Turns all enemies into their champion versions (if they have one).
FART SNDS	All sound effects are replaced with the sound of a fart.
B00B T00B	Applies a filter that makes the game look like it's being played through a cathode ray tube.
BRWN SNKE	Character leaves a trail of poop behind him as he walks.
SLOW 4ME2	Music playback speed/pitch is affected by character's walking speed.
KAPP A	Character spawns as grey, in reference to the Twitch emote.
GGGG GGGG	No gold rooms spawn.
DONT STOP	Character takes damage if they stop moving.
KEEP AWAY	Items mimic character movement (doesn't affect troll bombs).
DYSL EXIC	Ingame text is rearranged as though the character has trouble reading/speaking.
DYSL EXIA	Has the same effect as DYSL EXIC.
DRAW KCAB	All walk and shoot keys have been reversed.
C0NF ETT1	Enemies are dazed.
BL1N DEYE	Enemies are invisible (including bosses, fires, etc).
COME BACK	Enemies respawn once player leaves cleared room (includes bosses). New items won't drop.
XXXX XXZX	Unknown - Spoken by the fortune telling machine.
KEEP TRAK	Neither the map nor the health bar can be seen.
IMNO BODY	Character is completely invisible to the player.
PTCH BLCK	Character and their tears turn completely black.
FREE 2PAY	Start with 69 coins and the player must pay for every item.
PAY2 PLAY	Has the same effect as FREE 2PAY
FEAR M1NT	All enemies have permanent fear effect.
FRA1 DN0T	Every few seconds all enemies gain fear effect.
BL00 00DY	Gore is increased.
MED1 C1NE	All pill names and descriptions show ???.
FACE D0WN	All tarot cards are face down when picked up (So they have an unknown effect).
PAC1 F1SM	Enemies do not take damage. All doors stay open. When in a boss room, you must wait until the bosses health slowly drains before you can go to the next floor. This also applies to mini-bosses.
PAC1 F1ST	Same as PAC1F1SM
HART BEAT	The lower your health is, the slower the music is.
HARD HARD	Very Hard difficulty mode.
CLST RPHO	All enemies are friendly towards you. Flies spawned by Duke of Flies die instantly, but Dingle's dingleberries do not.
THEG HOST	Every 45 seconds, a ticking will begin, and after 5 seconds, Isaac will take 1/2 heart of damage. Damage increases to 1 heart in the womb and below. Having invincibility during the time when damage should be inflicted, such as by using My Little Unicorn, overrides the damage.
1337 HAXR	The game is much easier.

Fixed Seeds

The following seeds are fixed, which means you will get the same map every time. These are seeds considered to have "interesting" characteristics, and thus do not apply any special game-changing effect like the ones above.

"Need to test and make different category for fixed seeds and maybe per platform categories for some interesting seeds."

Seed	Effect
HAFD SVKX	No map available.
NV0W ZTSQ	Darkness curse.
YSB4 H4B8	Permanent Curse of the Lost. Loading Screen keeps showing the message "Are you sure you want me to die?".
9ZXW EQQL	No curse rooms.
1SAA AACE	Unknown. It does not work.
B911 99AC	Unknown.
N1CA L1SY	Unknown.
D1HQ 9XKH	From Caves I onwards, every boss fight will be a "double trouble" (except for Mom, Mom's Heart / It Lives, etc...)
AV7Z 4042	To play as Guppy. You must go in the cursed room which is at the start of the first floor and also have a bomb to blow the third chest.

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