Secret Floors Guide (Hidden Chambers)

Enter the Gungeon has a hidden chamber between each main floor (1.5 through 4.5). Defeating any secret floor boss flawlessly does not reward a Bala Mestra. This guide covers the requirements, step-by-step access, important notes, and first-visit rewards for each one.

Oubliette

Located between Castelo do Senhor de Chumbo and Balabirinto - Interior. Sewer-style layout full of garbage bags, toxic puddles, and harmless Balúnculo variants.

Cost: 2 keys (or Chaves Improvisadas Confiáveis / Broca as substitutes)

Steps to enter

1. Castelo do Senhor de Chumbo always contains a fireplace room — find the blue water barrel inside or in an adjacent room
2. Push the barrel next to the fireplace to extinguish the flames
3. Crawl into the fireplace and interact with the hidden switch
4. A hidden room with a trapdoor appears on the map — the trapdoor has two locks, each costing 1 key (2 total); Chaves Improvisadas Confiáveis or a Broca can substitute for normal keys

Notes

• Water barrels are fragile — enemy attacks and explosions destroy them, so position carefully during room clear
• If the barrel is gone, use Mega Encharcador, Vazamento de Resfriador
• After your first visit, the water barrel usually spawns inside or directly adjacent to the fireplace room on all future runs

Rewards and unlocks

• A small fixed room inside the Oubliette always contains the Insígnia Antiga, required for the Abadia da Vera Arma
• First visit unlocks Canhão de Lixo

Abadia da Vera Arma

Located between Balabirinto - Interior and Mina de Pólvora. Gothic monastery aesthetic with stronger enemies than the surface floors.

Cost: must first complete the Oubliette and retrieve the Insígnia Antiga

Steps to enter

1. Pick up the Insígnia Antiga from its fixed room inside the Oubliette — it occupies an armor slot and disappears the moment you take any damage
2. Carry the Insígnia Antiga through the rest of the Oubliette and all of Balabirinto - Interior without being hit
3. Find the altar room on Balabirinto - Interior — it contains seven large bullet warrior statues and looks one cell larger than a normal room on the map; it tends to appear near a shop or chest room
4. Place the Insígnia Antiga on the altar to open a staircase leading into the Abadia da Vera Arma

Notes

• Any hit destroys the Insígnia Antiga — if you're already low on health when entering the Oubliette, consider whether the escort is realistic
• Some rooms inside the Abadia da Vera Arma contain permanently Jammed enemies regardless of your Curse level — they deal and take significantly more damage
• The Abadia da Vera Arma always has a hidden room containing Buscador da verdade – Brother Albern; opening his chest yields Mentiras. This room spawns independently from normal secret room generation, so multiple secret rooms in one Abadia da Vera Arma run are common

Rewards and unlocks

• Boss drops both a normal boss reward and a Synergy Chest
• Simply entering for the first time unlocks Broche de Sangue and the "Reverence for the Dead" achievement — you do not need to clear the floor

Resourceful Rat's Lair

Located between Mina de Pólvora and Hollow. Mine tunnel layout with no shops and no normal chest rooms. The most complex prerequisites — plan ahead across multiple runs.

Cost: Chave Roída + 1 Chave + 2 Apagãos (the Chave can be swapped for Chave Mestra, AQUI-47, or Chaves Improvisadas Confiáveis; the Chave Roída has no substitute)

Preparation

• Hard prerequisite: the Chave Roída does not spawn in the shop at all until you have built the Bala que Pode Matar o Passado. You have to finish the four-component run in Bullet That Can Kill the Past Guide before this route opens up
• The Chave Roída first appears in a Balabirinto - Interior shop for 1000 Cápsulas; payment can be made in installments across runs, and once paid in full it costs 115 Cápsulas on every later run. Discount items never lower its price
• The Chave Roída can be stolen, but not with Gancho com Corda or the Controle Direcional hook (see How to Steal from Shops); if stolen before it has been paid off once, it returns next run at the price it was at
• Six Bilhete Irritante are scattered throughout all floors of Enter the Gungeon and appear randomly each run — pick them up whenever they show up. Each note ends with a cheese-wedge arrow indicating one direction in the maze; the more notes you have collected, the more of the correct sequence you know before entering the Lair

Steps to enter

1. On Mina de Pólvora, find a room with 2–4 rats running on the ground and clear it
2. Reveal the hidden trapdoor by walking repeatedly over suspicious floor tiles (a larger-than-normal dust cloud marks the right tile), spraying liquid on the ground, or using a Apagão anywhere in the room — short-range blank effects like Balas de Apagão won't work, and the trapdoor never spawns in a shop room
3. Open the trapdoor with a Chave and drop in
4. Walk along the minecart tracks to the end — do not ride the minecart (riding teleports you backwards repeatedly; walking is faster)
5. Use one Apagão at the dead end to open the first hidden passage. If you have Armadura, deliberately falling into the nearby pit reveals this passage too, saving a Apagão
6. Walk to the next dead end and use a second Apagão to open the second hidden passage. This one counts as a separate room with no pit, so the second Apagão cannot be saved unless you have another way to hurt yourself
7. Open the final hatch with the Chave Roída to enter the Lair

Notes

• Cachecol Ensanguentado lets you teleport past both hidden passages, skipping both Apagãos
• The Lair shows only a rat-holding-cheese animation instead of a real map
• Candle-carrying rats wander the floors — harmless normally (they die on contact and sometimes drop Cápsulas), but become Jammed and deal contact damage if you carry any Curse
• The maze is a sequence of six rooms, each with a choice of exit direction. Wrong once: sent back to the previous room. Wrong twice: elevator to the Hollow, ending your Lair run
• The correct sequence is fixed per save file and stays the same forever once discovered

Rewards and unlocks

• After defeating the O Rato Engenhoso, the reward room has eight pedestals with Coraçãos, Armadura, Chaves, Apagãos, Pedra Guon de Vidro, and Munição
• Four special chests in the room require Chave do ratos and contain Ementaler, Queijo Mordido, Saco Engenhoso, and Botas do Rato. Chave do ratos only drop during the third Punch-Out phase of the fight, up to six per fight
• The reward room also has a secret room with a snake hidden behind two locked doors — items can be dropped through the second door, so only one Chave do rato is needed to feed it
• Feed the snake 4 guns or items and it follows you as a companion until the Dragarma fight, where it defects and is absorbed to trigger the Advanced Dragun. That is the route to Cálice Furado and the "Advanced Slayer" achievement (the other is throwing a Ovo Estranho into fire)
• The snake refuses Televisão Avariada, Esponja, and Chaves Improvisadas Confiáveis — do not count on those to make up the four
• Alternatively, you can kick the O Rato Engenhoso into the snake to feed it
• After the reward room you can proceed to the Hollow normally, or spend a Chave do rato to skip directly to the Forja
• First visit unlocks Ovo Estranho

R&G Dept.

Located between Hollow and Forja. No connection to the other secret floors.

Cost: 1 Bala Mestra + 2 guns or items (sold to the Comprador rastejante in Hollow)

Steps to enter

1. Find the Comprador rastejante in Hollow
2. Sell the Bala Mestra and 2 items — the entrance opens immediately after the third item is sold, so sell the Bala Mestra last if you want to keep trading first

Notes

• The cost is steep: a Bala Mestra proves you cleared a boss without damage, and you lose two usable items on top of that
• R&G Dept. has no shop and sparse pickups
• The map outline is deliberately shaped like a handgun; after beating Agunim there is no exit elevator — you have to throw yourself off the rooftop arena to reach the Forja
• Only enter when your loadout has clear surplus — if your core weapon or survivability items are borderline, selling them for a bonus floor rarely pays off