Resourceful Rat's Lair

The **Resourceful Rat's Lair** (only referred to in-game as **???**) is a secret chamber in The Gungeon, accessed through a hidden passage found in the Black Powder Mine. It requires at least one key, two blanks, and the Gnawed Key to enter. As the name suggests, it is the domicile of the Resourceful Rat, and as such, nearly all floor features are themed around him. This includes the map only showing an animation of him holding a piece of cheese on a fishing rod and even the loading screen when entering the chamber.

Throughout the chamber, the player will encounter numerous rats holding candles. While these rats are harmless under normal circumstances, dying instantly upon player contact and occasionally yielding money, they can be jammed if the player has any curse, which will cause them to deal contact damage.

Like Bullet Hell, this floor features no shops and no chest rooms (unless one counts the reward room after beating the boss).

## How to access

Reaching the Resourceful Rat's Lair requires the Gnawed Key. It also requires a key to open the trapdoor (or any key replacing items like Shelleton Key or AKEY-47), and 2-3 blanks (or an explosive item or weapon that can open secret rooms).

* The AKEY-47 currently does not open the lock, as well as the lock for the trapdoor.
* In the Black Powder Mine, a room will have 2-4 rats running on the ground, as a hint. In this room there will be a locked trapdoor hidden by dust that can be revealed by walking on the respective tile multiple times, spraying it with Goop, water from the Mega Douser, or using a blank in the room (short-range blank effects, like blank bullets, will not reveal the trapdoor). A larger than normal dust cloud will appear when walking over the respective tile. The trapdoor cannot be in any shop.
* After unlocking the trapdoor with any normal key or key-replacing items, falling down it leads to a minecart on a track. Ride the minecart (or walk on the track) to the end, then use a blank to reveal a secret passage (activating a blank effect anywhere including the area before the track will reveal the room). Alternatively, if you have armor, taking damage (by falling into the pit) will reveal the first secret passage.
* At the end of the secret passage, use another blank to reach a room with another locked hatch.
	+ Alternatively, Bloodied Scarf can be used to teleport past both passages without using blanks.
	+ Armor cannot be used to open the second passage unless the player has other means of damaging themselves, as the first passage is considered a separate room from the one with the pit.
* Open the hatch with the Gnawed Key and enter it.
	+ Entering the Lair for the first time will unlock the Weird Egg.

### Notes

* The Gungeon Blueprint does not show the trapdoor's icon on the map.
* After falling down the trapdoor, there is a ladder to get back to the Black Powder Mine.
* If the player rides the minecart leading to the Gnawed Key hatch, the player will be repeatedly teleported backwards in the tunnel, making it appear longer than it actually is. This does not occur if the player does not ride the minecart, making it faster to walk on the tracks instead.
* The rats around the hatch can be jammed, and will deal contact damage.
* The Trusty Lockpicks, Drill, Shelleton Key, and AKEY-47 cannot open the hatch to the Resourceful Rat's Lair that requires the Gnawed Key.
* If the player kills the roaming rats and leaves the room unattended for a long time, the rat corpses will disappear.
* If the player has flight when entering the Resourceful Rat's Lair, the loading screen will be the default loading screen instead of the rat variant.
* When you enter the Resourceful Rat's boss fight room, he sits on a throne with dead Ser Junkans to the left and to the right of his throne.
* If the player teleports while falling into the trapdoor, the game will act like the player fell in a normal pit, dealing damage to the player.
* If the player enters the trapdoor before clearing the rat room, then teleports out of the minecart room and overrides that teleport, the rat floor will become softlocked.
	+ The player may be able to correct this with the use of an explosive weapon, which may be able to deal AOE damage through the door. Or through the use of Bloodied Scarf to teleport back into the room.
* If the player uses a flying item while trying to dust off the trapdoor, there will be no dust flying around, but the trapdoor will eventually be dusted off.

## Layout

Upon entering the floor, the player must fall down the hole in the room to the right to enter the maze.

### Maze

The maze consists of an endless grid of square rooms filled with enemies. The player must use the clues from the six Infuriating Notes in the Ammonomicon to determine the correct sequence of directions to travel. Each note ends with a piece of cheese pointing in a specific direction, and the six directions are in order of the six notes in the Ammonomicon. If the directions are successfully followed in order, the player will reach the Resourceful Rat. However, if the player wanders too long without finding the Resourceful Rat, they will simply be taken to an elevator to the Hollow. If the player attempts to take a shortcut in their path (e.g., if the path in the Infuriating Notes is up, right, up, left, left, left, and the player attempts the path up, up, left, left), the final room will contain the elevator to the Hollow even though both paths lead to the same room.

Since the correct sequence required to find the Rat is randomly generated,\* copying the route of another player is ineffective. However, once the correct route to the Rat has been found, it will stay the same for that player on all future playthroughs.

\* an exception to this can be found on the *Nintendo Switch* edition of the game, where the maze pattern for any copy is always down, right, down, up, down, up. (this is not the case with other console releases.)

### Post-Rat

After the Resourceful Rat has been fought, the player will be taken to a room with eight pedestals with 2 keys, 1 Glass Guon Stone, 1 Blank, 1 full heart, 1 armor, 1 ammo box, and 1 spread ammo box, along with four special chests that can be opened with special Rat Keys dropped by the Resourceful Rat. These chests always contain Elimentaler, Partially-Eaten Cheese, Resourceful Sack, and Rat Boots. The room also has a secret room, where a serpent is behind two locked doors that can be opened with Rat Keys.

* While there are two locked doors, the player only needs to use one Rat Key to feed the serpent.

After leaving the loot room, the player can either head to the Hollow or spend a Rat Key to skip to the Forge.

### Notes

* The maze in the Switch release of Gungeon is consistent at: down, right, down, up, down, up
* The directions to the Resourceful Rat are randomized for each player, but are the same between save files.
	+ As a result, the Infuriating Notes can be skipped on different save files. Doing so causes the Rat to say "What!? How did you find me? You are either exceedingly lucky or some kind of hacker!" during the intro.
* If the player has Mimic Tooth Necklace, a mimic with googly eyes will tell the player the Mimic Union is spread thin and can't provide mimics for the Rat Chests. Despite this, the Rat Chests can still be mimics.
* The chests can be opened using Trusty Lockpicks and Drill.
* The chests will drop a random  rank gun/item if the player has that item currently in their inventory.
	+ This does not apply if the chest in question is a Mimic, or if the chest's contents are revealed, making it possible to obtain multiple Rat Boots. Other duplicates will simply disappear upon pickup, however.
* It is possible to feed the Resourceful Rat to the serpent by kicking him towards it.
* Teleporting into a new room using the Bloodied Scarf may cause the game to softlock. (PC)
* The room in which the serpent is held will not be open unless the player has defeated the third phase of the Rat fight during that run.
	+ This can be bypassed by using the Bloodied Scarf and teleporting to the place in which the room would usually be. This causes part of the black area surrounding the room to brighten up and turn light grey where the room would usually appear.
		- The player can feed the serpent when teleporting in. However, feeding the serpent the Bloodied Scarf will result in a softlock, as the player will have no way to escape the cell.
* The Resourceful Rat will not steal items left on the ground on this floor. However, since rooms cannot be re-entered once left, this is only observable when using items that transport the player back to the beginning of the chamber, such as Gun Soul.

## Enemies

* In addition, the skeletal rat-like minions summoned in the Resourceful Rat Boss Fight can appear in large quantities.

## Rooms

Most rooms in the lair share the same square-like shape with an exit tunnelling on each side. The contents of these rooms are as follows:

* 2 random Shotgun Kin variants and 1 Mutant Shotgun Kin (all 3 being jammed) guarding an Ammomancer.
* 2 Lead Maidens.
* 2 Chance Kin accompanied by a player-seeking Dead Blow.
* 1 of each Shotgun Kin variant (excluding Executioners and Shotgrubs), a Shotgat, and a Creech. Following this either when all enemies are slain or nearly all, a Jamerlengo appears.
* A jammed Chancebulon. This wave is followed by another jammed Chancebulon together with 2 regular Chancebulons.
* An on-spawning army of Rat minions.
* A horde of Spents together with a Gunreaper. After a fair few are slain, 2 Skullets and a Jammomancer join the fight.
* An empty room.
* 2 Shelletons.
* 2 Phaser Spiders.
* 2 Chancebulons and a Misfire Beast.
* 2 Pinhead, 1 Killithid, and 1 Cubulon.

Every room has TNT, Tables, Coffins, and Phaser Spider webs strewn about randomly.

## Trivia

* Despite there being no usable map on the Resourceful Rat's Lair, the boss entrance still has a teleporter.