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 Munizione eccelsa. This guide covers the requirements, step-by-step access, important notes, and first-visit rewards for each one.

Oubliette

Located between Segreta del Signore del piombo and Gungeon vero e proprio. Sewer-style layout full of garbage bags, toxic puddles, and harmless Pallottoloide variants.

Cost: 2 keys (or Fidati grimaldelli / Trapano as substitutes)

Steps to enter

1. Segreta del Signore del piombo 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); Fidati grimaldelli or a Trapano 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 Idromegablaster, Perdita di refrigerante
• 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 Vecchio stemma, required for the Abbazia della Vera arma
• First visit unlocks Cannone immondiziere

Abbazia della Vera arma

Located between Gungeon vero e proprio and Miniera di polvere nera. Gothic monastery aesthetic with stronger enemies than the surface floors.

Cost: must first complete the Oubliette and retrieve the Vecchio stemma

Steps to enter

1. Pick up the Vecchio stemma from its fixed room inside the Oubliette — it occupies an armor slot and disappears the moment you take any damage
2. Carry the Vecchio stemma through the rest of the Oubliette and all of Gungeon vero e proprio without being hit
3. Find the altar room on Gungeon vero e proprio — 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 Vecchio stemma on the altar to open a staircase leading into the Abbazia della Vera arma

Notes

• Any hit destroys the Vecchio stemma — if you're already low on health when entering the Oubliette, consider whether the escort is realistic
• Some rooms inside the Abbazia della Vera arma contain permanently Jammed enemies regardless of your Curse level — they deal and take significantly more damage
• The Abbazia della Vera arma always has a hidden room containing Cercatore della verità – Brother Albern; opening his chest yields Menzogne. This room spawns independently from normal secret room generation, so multiple secret rooms in one Abbazia della 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 Spilla di sangue and the "Reverence for the Dead" achievement — you do not need to clear the floor

Resourceful Rat's Lair

Located between Miniera di polvere nera and Hollow. Mine tunnel layout with no shops and no normal chest rooms. The most complex prerequisites — plan ahead across multiple runs.

Cost: Chiave roditrice + 1 Chiave + 2 Obliteratores (the Chiave can be swapped for Skelechiave universale, AKiave-47, or Fidati grimaldelli; the Chiave roditrice has no substitute)

Preparation

• Hard prerequisite: the Chiave roditrice does not spawn in the shop at all until you have built the Proiettile ammazzapassato. You have to finish the four-component run in Bullet That Can Kill the Past Guide before this route opens up
• The Chiave roditrice first appears in a Gungeon vero e proprio shop for 1000 Bossoli; payment can be made in installments across runs, and once paid in full it costs 115 Bossoli on every later run. Discount items never lower its price
• The Chiave roditrice can be stolen, but not with Rampino or the Tasti direzionali 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 Messaggio indisponente 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 Miniera di polvere nera, 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 Obliteratore anywhere in the room — short-range blank effects like Proiettili obliteranti won't work, and the trapdoor never spawns in a shop room
3. Open the trapdoor with a Chiave 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 Obliteratore at the dead end to open the first hidden passage. If you have Corazza, deliberately falling into the nearby pit reveals this passage too, saving a Obliteratore
6. Walk to the next dead end and use a second Obliteratore to open the second hidden passage. This one counts as a separate room with no pit, so the second Obliteratore cannot be saved unless you have another way to hurt yourself
7. Open the final hatch with the Chiave roditrice to enter the Lair

Notes

• Sciarpa insanguinata lets you teleport past both hidden passages, skipping both Obliteratores
• 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 Bossoli), 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 Ratto arraffatore, the reward room has eight pedestals with Cuores, Corazza, Chiaves, Obliteratores, Germa di vetro, and Munizioni
• Four special chests in the room require Chiave del rattos and contain Elemmentaler, Formaggio senza spicchio, Sacco arraffatore, and Stivali da ratto. Chiave del rattos 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 Chiave del ratto is needed to feed it
• Feed the snake 4 guns or items and it follows you as a companion until the Armadrago fight, where it defects and is absorbed to trigger the Advanced Dragun. That is the route to Graal crivellato and the "Advanced Slayer" achievement (the other is throwing a Uovo strano into fire)
• The snake refuses Televisore in avaria, Spugna, and Fidati grimaldelli — do not count on those to make up the four
• Alternatively, you can kick the Ratto arraffatore into the snake to feed it
• After the reward room you can proceed to the Hollow normally, or spend a Chiave del ratto to skip directly to the Forgia
• First visit unlocks Uovo strano

R&G Dept.

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

Cost: 1 Munizione eccelsa + 2 guns or items (sold to the Mercante strisciante in Hollow)

Steps to enter

1. Find the Mercante strisciante in Hollow
2. Sell the Munizione eccelsa and 2 items — the entrance opens immediately after the third item is sold, so sell the Munizione eccelsa last if you want to keep trading first

Notes

• The cost is steep: a Munizione eccelsa 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 Forgia
• 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