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

Oubliette

Located between 리드 로드의 성채 and 총굴 본관. Sewer-style layout full of garbage bags, toxic puddles, and harmless 총탄 일족 variants.

Cost: 2 keys (or 믿음직한 자물쇠 따개 / 드릴 as substitutes)

Steps to enter

1. 리드 로드의 성채 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); 믿음직한 자물쇠 따개 or a 드릴 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 메가 도저, 냉각수 누출
• 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 오래된 문장, required for the 진정한 총의 수도원
• First visit unlocks 쓰레기 캐논

진정한 총의 수도원

Located between 총굴 본관 and 화약 탄광. Gothic monastery aesthetic with stronger enemies than the surface floors.

Cost: must first complete the Oubliette and retrieve the 오래된 문장

Steps to enter

1. Pick up the 오래된 문장 from its fixed room inside the Oubliette — it occupies an armor slot and disappears the moment you take any damage
2. Carry the 오래된 문장 through the rest of the Oubliette and all of 총굴 본관 without being hit
3. Find the altar room on 총굴 본관 — 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 오래된 문장 on the altar to open a staircase leading into the 진정한 총의 수도원

Notes

• Any hit destroys the 오래된 문장 — if you're already low on health when entering the Oubliette, consider whether the escort is realistic
• Some rooms inside the 진정한 총의 수도원 contain permanently Jammed enemies regardless of your Curse level — they deal and take significantly more damage
• The 진정한 총의 수도원 always has a hidden room containing 진리 탐구자 – 알번 형제; opening his chest yields 뻥이에요. This room spawns independently from normal secret room generation, so multiple secret rooms in one 진정한 총의 수도원 run are common

Rewards and unlocks

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

Resourceful Rat's Lair

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

Cost: 갉아 먹힌 열쇠 + 1 열쇠 + 2 공포탄s (the 열쇠 can be swapped for 쉘레톤 열쇠, 에이키-47, or 믿음직한 자물쇠 따개; the 갉아 먹힌 열쇠 has no substitute)

Preparation

• Hard prerequisite: the 갉아 먹힌 열쇠 does not spawn in the shop at all until you have built the 과거를 제거할 수 있는 총탄. You have to finish the four-component run in Bullet That Can Kill the Past Guide before this route opens up
• The 갉아 먹힌 열쇠 first appears in a 총굴 본관 shop for 1000 탄피; payment can be made in installments across runs, and once paid in full it costs 115 탄피 on every later run. Discount items never lower its price
• The 갉아 먹힌 열쇠 can be stolen, but not with 닻 모양 갈퀴 or the 방향 패드 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 짜증나는 메모 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 화약 탄광, 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 공포탄 anywhere in the room — short-range blank effects like 공포탄 총탄 won't work, and the trapdoor never spawns in a shop room
3. Open the trapdoor with a 열쇠 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 공포탄 at the dead end to open the first hidden passage. If you have 갑옷, deliberately falling into the nearby pit reveals this passage too, saving a 공포탄
6. Walk to the next dead end and use a second 공포탄 to open the second hidden passage. This one counts as a separate room with no pit, so the second 공포탄 cannot be saved unless you have another way to hurt yourself
7. Open the final hatch with the 갉아 먹힌 열쇠 to enter the Lair

Notes

• 피묻은 목도리 lets you teleport past both hidden passages, skipping both 공포탄s
• 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 탄피), 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 쥐갈공명, the reward room has eight pedestals with 하트s, 갑옷, 열쇠s, 공포탄s, 유리 구온석, and 탄약
• Four special chests in the room require 쥐 열쇠s and contain 치즈뿌리개, 일부분 먹은 치즈, 쥐갈공명의 자루, and 쥐 장화. 쥐 열쇠s 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 쥐 열쇠 is needed to feed it
• Feed the snake 4 guns or items and it follows you as a companion until the 드래건 fight, where it defects and is absorbed to trigger the Advanced Dragun. That is the route to 뻥뻥 성배 and the "Advanced Slayer" achievement (the other is throwing a 기묘한 알 into fire)
• The snake refuses 고장 난 텔레비전, 스펀지, and 믿음직한 자물쇠 따개 — do not count on those to make up the four
• Alternatively, you can kick the 쥐갈공명 into the snake to feed it
• After the reward room you can proceed to the Hollow normally, or spend a 쥐 열쇠 to skip directly to the 대장간
• First visit unlocks 기묘한 알

R&G Dept.

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

Cost: 1 탄환의 주인 + 2 guns or items (sold to the 판매 괴물 in Hollow)

Steps to enter

1. Find the 판매 괴물 in Hollow
2. Sell the 탄환의 주인 and 2 items — the entrance opens immediately after the third item is sold, so sell the 탄환의 주인 last if you want to keep trading first

Notes

• The cost is steep: a 탄환의 주인 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 아구님 there is no exit elevator — you have to throw yourself off the rooftop arena to reach the 대장간
• 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