Secret Seeds

Isaac is completely invisible, however you can still see the light effect surrounding him.

Gives you a hard timer of 30 minutes to beat the game. After 29:45 a timer starts ticking and at 30:00 you will take damage every second.

Music is permanently sped up.

Music is permanently slowed down.

Endless run, where every floor is the basement! Due to how the item spawning mechanics work, after the item pool is exhausted, every item will become the Breakfast health up item.

Turns all enemies invisible.

Increased gore effects when enemies die.

Applies a filter to the game which makes it look like a CRT television screen.

Taking any damage instantly kills you.

Isaac leaves a trail of poop behind him as he walks.

All pickups are now covered in a colour similar to the floor, making them harder to see.

The player sprite is removed and replaced with a brown coloured shadow which is similar to the floor colour.

Turns every eligible enemy into a champion version.

Gives Isaac a Santa hat! (Same effect as 'H0H0 H0H0' - Added in v1.04)

All enemies have a permanent charm effect and will attack each other if hostile.

Enemies respawn when you leave the room and come back.

All enemies have a permanent concussion effect, making them walk around the room dazed.

Gives curse of the unknown on every floor.

Isaac takes damage if he stops moving.

Inverts your movement and firing controls.

Ingame text is re-arranged.

All Tarot Cards when picked up are face down so their effect is always unknown.

Does what it says on the tin - Sound effects are replaced with fart noises.

All enemies have a permanent fear effect.

All enemies have a fear effect which turns on and off every few seconds, causing enemies to run away sometimes.

Starts you with 69 coins and makes it so you have to purchase all of your items and pickups.

All damage does 1 full heart for every floor.

The lower your health is, the slower the music is.

Gives Isaac a Santa hat! (Same effect as 'CHRS TMAS' - Added in v1.04)

Turns Isaac's sprite grey coloured like the twitch.tv Kappa emote.

Pickups mimic player movement.

Removes all parts of the UI overlay, including map, consumable count, health etc.

Causes the Player 2 coop baby to be invincible.

Music is permanently slowed way way down (More than the ANDA NTE seed).

All pill text (names and descriptions) are replaced with ???.

Enemies and bosses cannot be killed, all doors remain always open and bosses have their health slowly drained.

Music is permanently sped up a lot (More than the ALLE GR0 seed).

Turns Isaac into a jet black shadow.

Music speed changes based on how fast you are walking.

Tears have a slight glow around them (Hardly noticable unless you have Curse of Darkness).

Isaac has no face!

Every 45 seconds a ticking sound will start and after 5 seconds Isaac takes damage. A reference to when Edmund stated there would be a Spelunky ghost-like mechanic in the game and it was taken out of context by some of the community.

Gives Isaac a teeny-tiny head.

Gives Isaac a HUGE head.

Isaac, Enemies, Consumables and Items all have a brown filter and blend in with the floor (Similar to CAM0 K1DD / CAM0 F0ES).

Ice movement physics, causing you to slide everywhere

Permanent Curse of The Darkness effect on all floors.

Permanent Curse of The Labyrinth effect on all floors.

Permanent Curse of The Lost effect on all floors.

Permanent Curse of The Unknown effect on all floors.

Permanent Curse of The Maze effect on all floors.

Permanent Curse of The Blind effect on all floors.

Permanent Curse of The Curse effect on all floors (All non-special doors are cursed room doors, similar to challenge #10 'CURSED!')

Removes all chance to get Curse of the Darkness.

Removes all chance to get Curse of the Labyrinth.

Removes all chance to get Curse of the Lost.

Removes all chance to get Curse of the Blind.

Removes all chance to get Curse of the Maze.

Total curse immunity - Removes all curses!

Removes the exit door in each boss room, forcing you to go down the trapdoor straight after the fight.

All consumables disappear after about 7 seconds.

Tears can now only be fired by walking in the direction you want them to. Normal tear firing controls are disabled.

Tears can now only be fired by walking in the OPPOSITE direction you want them to. Normal tear firing controls are disabled.

Axis-aligned controls - Movement is locked to 90 degree angles only

G Fuel! — spawns a G FUEL! item in the starting room of each floor. Each copy has different effects and adds excessive "gamer style" visuals and sound. Blacklists a set of items including Brimstone, Mom's Knife, Dr. Fetus and Tech X.

SuperHot — while Isaac is not moving, time runs extremely slowly. Isaac's own speed and fire rate stay normal.

Retro vision — the screen has a permanent Retro-Vision pill effect.