GB Bug

Item Icon
Pickup Quote	"Double tap glitch"
Entity ID	5.100.405
Item Pool	Secret Room Treasure Room Secret Room Shop
Quality	0
Item Tags
Collection Grid	(page 4, column 20, row 2) (page 4, column 20, row 2) (page 4, column 1, row 3)
Unlock Method	Defeat Ultra Greed as Eden

GB Bug is an unlockable passive item added in The Binding of Isaac: Afterbirth.

Effects

• Spawns a familiar that bounces diagonally around the room, deals 8 damage per tick or 120 damage per second and applies a random status effect to enemies it comes in contact with. The familiar also has a chance to re-roll pickups that it passes over into other pickups, chests, or items, in an uncleared room only (with at least one enemy alive).
• Spawns a familiar that follows Isaac. Double tapping the fire button launches it forward, causing it to reroll the first monster, trinket, or pickup it hits. It respawns after clearing a room.
  • If it cannot reroll an enemy (e.g. a boss), it will deal 8 damage instead.
  • It can also be used to reroll trinkets into pickups.
  • Pickups may also be rerolled into chests.

Algorithm

GB bug uses the following algorithm to determine what the morphed pickup will be:

local chestPickupVariants = {
  PickupVariant.PICKUP_CHEST, -- 50
  PickupVariant.PICKUP_BOMBCHEST -- 51
  PickupVariant.PICKUP_SPIKEDCHEST -- 52
  PickupVariant.PICKUP_ETERNALCHEST -- 53
  PickupVariant.PICKUP_MIMICCHEST, -- 54
  PickupVariant.PICKUP_OLDCHEST, -- 55
  PickupVariant.PICKUP_WOODENCHEST, -- 56
  PickupVariant.PICKUP_MEGACHEST, -- 57
  PickupVariant.PICKUP_HAUNTEDCHEST, -- 58
  PickupVariant.PICKUP_LOCKEDCHEST, -- 60
  PickupVariant.PICKUP_REDCHEST, -- 360
  PickupVariant.PICKUP_MOMSCHEST, -- 390
}
if (contains(chestPickupVariants, pickupVariant) and (pickupSeed:Next() % 5) == 0) or (pickupSeed:Next() % 10) == 0 then
  local newVariant
  if (pickupSeed:Next() & 3) == 0 then
    newVariant = PickupVariant.PICKUP_LOCKEDCHEST
  else
    newVariant = PickupVariant.PICKUP_CHEST
  end
  pickup:Morph(pickup.Type, newVariant, 0, true, false, false)
else
  pickup:Morph(pickup.Type, 0, 1, true, false, false)
end

Notes

• GB Bug can block projectiles.
• GB Bug does more damage per second than The Peeper, with the added random status chance.
• GB Bug is able to reroll Throwable Bombs into normal consumables. After doing so, the corresponding Bomb Grimace will generate another Throwable Bomb, making it able to generate a potentially large amount of free consumables.
• The Twins: the familiar can be duplicated even if it hasn’t respawned; by constantly moving to new rooms, GB Bug can constantly respawn, allowing pickups to be rerolled indefinitely.

Trivia

• Before Repentance, GB Bug's pickup quote was "Game breaking bug, right away!"
• This item's in-game appearance may be a reference to "Missingno.", a famous bug occurring in the first Pokémon games.
• As Edmund confirmed on Twitter the pickup quote "Game breaking bug, right away!" is a reference to a quote by Phil Fish in Indie Game: The Movie, where he says the same words when a bug is discovered in the game "FEZ" on the first day it is being shown at PAX.

Seeds

PC 9B7E 3G67 (Treasure Room adjacent to spawn, curse of the labyrinth)

PC GZWT H4LE (First floor Treasure Room)

PC 44W2 XHJ8 (Treasure Room adjacent to spawn)

PC OCML SLQN (First floor Treasure Room)

The Binding of Isaac: Rebirth
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