Hibernation forms part of the core gameplay loop of Rain World, serving as the end goal of each cycle. Shelters, dens, or hibernation pods are self-sealing chambers scattered around regions, used for hibernating: resting in them is the only way to finish a cycle, save the game, and progress karma level. After hibernating, the save's cycle count as well as cycle timers throughout the world advances.
Hibernation is initiated by entering a Shelter room with sufficient food to sleep through the rain. The total amount of food required to sleep in a Shelter is indicated by the food meter at the bottom left corner of the screen, which can be viewed at any time by tapping or holding the Map button.
The food pips necessary to hibernate varies between Slugcats; the dividing line indicates how many pips are required to sleep, with any pips to the right being stored for the next cycle:
Hibernation can be initiated at any point during a cycle, but must be done before the rain kills Chat-limace at latest. Entering the chamber of a Shelter and staying still while having the minimum amount of filled food pips initiates the sealing process and brings up the hibernation screen. Shelter doors remain open as long as movement inputs are being performed. If lacking the minimum food while inside a Shelter, any unfilled food pips below the line flash red. If there is enough food for hibernation present in the Shelter, it is automatically consumed and hibernation is initiated. Similarly, any Fleurs de Karma inside Shelters are automatically consumed when hibernating. If it is raining, hibernation is forced as soon as Slugcat is inside the chamber regardless of food pips.
Shelter interiors are not affected by the rain, and it is possible to stay indefinitely inside the tunnel into the main Shelter chamber without being killed or forced to hibernate.
Once at the hibernation screen, the amount of food consumed during the cycle is shown, as well as current karma level and passages if any are in progress or attained. It is also possible to view the map by holding the map button. Holding the map button also speeds up menu animations.
Hibernating inside a Shelter
Starvation
Hibernation can be forced without sufficient food as long as at least one food pip is full. Starvation is initiated by holding in a Shelter. While attempting to starve, the dividing line on the food meter begins to shake and move to the left to meet current food pip count. Letting go of before the line meets the final pip cancels the starvation attempt. Alternatively, entering a Shelter while it is raining and without sufficient food automatically forces starvation. If there are sufficient food items stored in the Shelter, starvation is not possible. Upon successfully initiating starvation, all pips, as well as karma reinforcement if present, are consumed, and the hibernation screen is brought up with a warning that progress has not been saved.
Starvation effectively acts as a double or nothing bet: it is a useful tool that grants the chance to gain further progress without sufficient food at the expense of severe drawbacks and the risk of losing it all when dying. The cycle after initiating starvation is referred to as a "starve cycle".The unique starvation death screen.Survivor recovers from starving state
During a starve cycle, Slugcat requires a completely full food bar in order to hibernate again and receives significant debuffs. Their throwing skill is reduced to Moine's, lowering damage and limiting slide-throwing. If exerted too much, such as by excessive jumping, they enter an exhausted state where they close their eyes, moving slower and having weaker jumps whilst they attempt to regain composure - similar to exiting water with very little oxygen left. When completely exhausted, they collapse and drop any items currently being held. They also become a paler color, visibly skinnier, and weigh less. Completely filling the food bar removes the debuff and restores Slugcat's original color.
Dying or quitting while starving results in being rolled back to the last successful save, undoing any reputation changes and returning Slugcat to the last Shelter they hibernated in before the starve cycle. However, map progress is still retained. Attempting to starve a second time after starving results in death with a unique death screen.
Exiting to the main menu during the hibernation screen allows the player to resume the game in the starving state; however, fully exiting and relaunching the game does not preserve this. Quitting out after starting the starve cycle counts as a death even during the 30 second grace period.
Line moving as hibernation is forced
Line moving to the right on the hibernation screen, reflecting the need to fill the food bar
Bugs & Exploits
Due to starvation's unusual interactions with how the game saves progress, there are several bugs and exploits associated with it.
Passage progress gained on starves is retained even if the starve cycle is not successful (not accounting for certain passages losing progress after dying). Le Chef is the only exception to this exploit as reputation changes are rolled back after dying.
Karma caching is an exploit that allows for quickly gaining karma without having to survive or advance cycles. It is executed by starving, entering the next cycle, and then quitting out before the 30 second quit-out threshold. This retains the karma increase while reverting to the cycle before the starve, and can be chained multiple times in a row to quickly raise karma as much as needed. This exploit can also be used to obtain Le Survivant, L'Ami (provided there is a tamed Lizard present in the Shelter), and Le Saint passages. This is predominantly used in speedruns.
Double-spawning, while not exclusively triggered by starvation, is a bug that doubles all den spawns in a region if the cycle in which it is loaded for the first time in a playthrough ends in a starve. Due to how starving does not save progress, the game loads the list of spawns again as it believes the region has been entered for the first time again. Dying after starving reverts the doubled spawns, and the bug can no longer be triggered for that region. This is predominantly used in scoreruns.
Starving into Echos is an exploit that involves starving and visiting an Echo, causing progress to be reverted back to the cycle before starving while still maintaining the karma increase along with passage progress made the cycle before visiting the Echo. This is predominantly used in Chasseur runs to conserve cycles or to warp back to specific Shelters.
(Cigalamar) starve flight is an exploit caused by an unusual interaction between Chat-limace's reduced weight when starving, jumping states and the effect white Squidcadas have on Slugcat's gravity. The most common method utilized to trigger it is backflipping while holding a Squidcada, after which height can be gained infinitely by holding the jump button. Starve flight can be used to clear long distances while staying in the air, making it useful for crossing gaps that cannot be cleared by typical jumps, or the large patches of Herbe Ver that can be found in Pléiade des fermes. Flight can be stopped by grabbing a pole or letting go of the Squidcada.
It should be noted that with the upcoming parity patch these are all subject to change.
Broken Shelters
Some shelters are permanently broken for certain Slugcats. Following is a list of those shelters and for whom they are broken.
These shelters still exist and can be visited when they are broken, but they do not function, and their pipe entrances are unmarked.
The shelter Slugcat awakens in does not function for 1 cycle during shelter failure.
A Shelter displaying many item icons. Bébés Vermimouches in the Shelter should be displayed, but are beyond the limit.
Objects (other than Fleurs de Karma), food, creatures (other than Chauve-sourillons), and corpses can be stored indefinitely inside Shelters as long as they either cannot get out on their own or are not taken out by Farfouilleurs. They persist no matter how many cycles pass and when the region is no longer loaded. The map displays up to a maximum of 50 icons underneath the Shelter to represent what is stored inside it.
Creatures are capable of entering Shelters and may pursue prey into one if they witness them entering it. It is also possible for creatures to enter even when the Shelter doors are closing, resulting in them being considered inside the Shelter and being placed inside the main chamber when the next cycle begins. As a soft-lock prevention measure, any creatures present in a Shelter at the beginning of a cycle are pacified for 15 seconds as long as they are not aggravated. However, this does not appear to work with larger Mille-pattes, meaning care should be taken to lure them away from Shelter entrances and/or kill them if planning to hibernate when one is present. Occasionally, hibernation can be inadvertently triggered if a creature brings an incapacitated Slugcat into a Shelter chamber while they meet the food requirement.
When brought into a Shelter and hibernated with, Œufs de Vermimouche hatch into several Infant Noodleflies, which follow Slugcat until an Adult Noodlefly is encountered, at which point they begin following the adult.
It is possible for objects, creatures, and corpses to clip out of Shelter geometry, in which case they cannot be recovered unless the cycle is restarted via quitting out.
Passages can be viewed and used from the hibernation screen. Passage progress is displayed in bars extending radially from the karma symbol on the hibernation screen, which glow a bright white when completed. Passages with pips have requirements that can be completed non-consecutively, whereas passages with bars must be contributed to consecutively until the passage is attained. The only exception is Chieftain, which instead is tied to global reputation and can be revoked if enough Scavenger reputation is lost.
Selecting the passage button consumes the oldest attained passage, displaying the passage art before prompting the player to choose a region to travel to. Buttons at the sides allow for scrolling through each region that has been visited previously and Carte can be held to pick a specific Shelter to spawn in (being left random if not selected). Leaving the passage screen at any point before confirming cancels its usage and brings up the main menu screen.
When Remix is enabled, an unlock tracker appears in the upper right corner of the Hibernation screen. This tracker features color-coded diamonds that correspond to the Arena tokens scattered within Regions.
Each dot represents a region, which, from left to right, follows the order of the Wanderer passage. An arrow indicates the region the player is currently in. Regions that have yet to be entered appear as grey crosses with no diamonds.
Blue diamonds represent Creatures and Object unlockables. Yellow diamonds represent unlockable Arenas levels. If More Slugcats Expansion is enabled, red diamonds represent Safari regions, and green diamonds represent playable characters in Arena. In Maître-Lancier's campaign, grey diamonds represent Broadcasts.
Glowing Slugcat
Glowing Slugcat resting in a Shelter and disappearing when Monk enters.
The Glowing Slugcat appears in Moine's and Artificier's campaigns upon entering a shelter just before a dream sequence is activated. They emit an intense glow that illuminates the entire shelter and disappear once Slugcat enters the shelter. The Glowing Slugcat can reappear in other shelters, even after being seen before.
SPOILER WARNING: Ending This section contains major plot details from the end of the game. If you have not yet completed the game on any difficulty, then read no further!
Whilst progressing through the game, special one-time cutscenes occasionally play after hibernating when certain conditions have been met. They are indicated by the screen fading to black before getting to view current karma and passage progress, and can be viewed for any duration until the continue button is selected.
Dreams can be separated into 4 categories, in descending order of priority: Iterator, Void, Overseer and Family dreams. All of them can be predicted thanks to their defined requirements.
Iterator dreams happen after encountering Looks to the Moon or Five Pebbles for the first time. Depending on actions taken during the first visit, there are two variants of the dream that can play after visiting Moon.
Void dreams happen whilst inside Sous-terrain. The upwards dream plays when Sheltering in Subterranean for the first time and takes higher priority over the downwards dream, which plays when Sheltering for the first time inside SB_S01 (the final Shelter in Filtration System above the entrance to Depths) - or the second time if the first time triggered the upwards dream instead.
Overseer dreams start happening after at least four cycles have passed successfully, and at least two cycles must pass before the next Overseer dream may play. Additionally, they only play if the Overseer does not dislike Slugcat. Overseer dreams have a specific order; progression through it cannot go backwards, but may skip a dream if the requirements of the following one are met earlier. The first Overseer dream plays if only the basic requirements are met; the second one plays if the Overseer has shown projections of Moon during the previous cycle, and Slugcat has slept in Déchetterie or Citadelle obscure at least two cycles before; the third Overseer dream plays in Littoral.
Family dreams only happen if no other dream has higher priority, and the previous dream was at least three cycles before. Like Overseer dreams, their order of appearance is defined. The first family dream plays if only the basic requirement is met; the second family dream plays at least eight cycles after the first one; the third family dream plays at least seven cycles after the second one; the final family dream (which shares art with the upwards Void dream) plays at least 15 cycles after the third one.
Spoilers end here.
Contenu exclusif à Downpour
Cette section parle de contenu exclusif au DLC Downpour. Ce contenu n'est pas disponible dans le jeu de base.
A shelter failure is a rare event in which the shelter Slugcat hibernates in opens prematurely, causing the shelter to flood and Slugcat to awaken while it is still raining.
Le contenu exclusif à Downpour s'arrête ici.
Trivia
At release, starving at any point simply resulted in death (using the same death screen currently used for starving twice in a row). This was changed to the current starvation mechanic with 1.5.
In alpha versions, Shelters were considerably different visually, exhibiting two airlocks on the sides with two pipe connections outside each one. They can be seen in the Slugpups video.
Vautours, Oiseaux de Miró, Plantes Poteaux, Goémonstres, and Cerfs Pluie die if they are located in a Shelter when the cycle ends, and each of their corpses despawns on the next cycle. They're incapable of travelling through pipes on their own, so this can be achieved by moving their corpses into the Shelter (If Remix is enabled, requires "Vanilla Exploits" to be possible for the listed creatures other than Vautours de Miró) or with exploits.
Starting from Remix's release until 1.9.14, enabling Remix resulted in a limit of at most 9 items of the same type possible to store. Key items, Spears stuck in walls or creatures, and held items were excluded from the counter.
In Outer Expanse, three large shelters can be found, which use Karma Gate style doors. These shelters are called Ancient Shelters.
SPOILER WARNING This section contains major plot details. If you have not made significant progress in the game, then it is recommended that you read no further!
Moine
Survivant
Chasseur
Gourmand
Artificier
Ruisselet
Maître-Lancier
Saint
Inv
Chat-limace at latest. Entering the chamber of a Shelter and staying still while having the minimum amount of filled food pips initiates the sealing process and brings up the hibernation screen. Shelter doors remain open as long as movement inputs are being performed. If lacking the minimum food while inside a Shelter, any unfilled food pips below the line flash red. If there is enough food for hibernation present in the Shelter, it is automatically consumed and hibernation is initiated. Similarly, any 
Fleurs de Karma inside Shelters are automatically consumed when hibernating. If it is raining, hibernation is forced as soon as Slugcat is inside the chamber regardless of food pips.
Hibernating inside a Shelter
.png)
Line moving as hibernation is forced
Line moving to the right on the hibernation screen, reflecting the need to fill the food bar
Le Chef is the only exception to this exploit as reputation changes are rolled back after dying.
Le Survivant, 
L'Ami (provided there is a tamed Lizard present in the Shelter), and 
Le Saint passages. This is predominantly used in speedruns.
Echos is an exploit that involves starving and visiting an Echo, causing progress to be reverted back to the cycle before starving while still maintaining the karma increase along with passage progress made the cycle before visiting the Echo. This is predominantly used in 
Cigalamar) starve flight is an exploit caused by an unusual interaction between 
Herbe Ver that can be found in 
Pléiade des fermes. Flight can be stopped by grabbing a pole or letting go of the Squidcada.
Complexe industriel
Littoral
Entrepôt de tuyaux
Superstructure submergée
Ultra étendue
Bébés Vermimouches in the Shelter should be displayed, but are beyond the limit.
Chauve-sourillons), and corpses can be stored indefinitely inside Shelters as long as they either cannot get out on their own or are not taken out by 
Farfouilleurs. They persist no matter how many cycles pass and when the region is no longer loaded. The map displays up to a maximum of 50 icons underneath the Shelter to represent what is stored inside it.
Mille-pattes, meaning care should be taken to lure them away from Shelter entrances and/or kill them if planning to hibernate when one is present. Occasionally, hibernation can be inadvertently triggered if a creature brings an incapacitated Slugcat into a Shelter chamber while they meet the food requirement.
Grosses Araignées, 
Araignées Éclabousseuses, all non-Infant 
Perce-oreilles, 
Vermimouches Adultes, and 
Putréfaction cysts die if inside a Shelter when the cycle ends. 
Agrégapèdes and the corpses of 
Mille-pattes Rouges will despawn on the next cycle if this happens.
Œufs de Vermimouche hatch into several Infant Noodleflies, which follow Slugcat until an Adult Noodlefly is encountered, at which point they begin following the adult.
Chauve-sourillons disappearing after hibernation
Grosse Araignée dying after hibernation
Œuf de Vermimouche hatching after hibernation
More Slugcats Expansion is enabled, red diamonds represent 
SPOILER WARNING: Ending
Five Pebbles for the first time. Depending on actions taken during the first visit, there are two variants of the dream that can play after visiting Moon.
Sous-terrain. The upwards dream plays when Sheltering in Subterranean for the first time and takes higher priority over the downwards dream, which plays when Sheltering for the first time inside SB_S01 (the final Shelter in Filtration System above the entrance to Depths) - or the second time if the first time triggered the upwards dream instead.
Déchetterie or 
Citadelle obscure at least two cycles before; the third Overseer dream plays in 
Vautours, 
Oiseaux de Miró, 
Plantes Poteaux, 
Goémonstres, and 
Cerfs Pluie die if they are located in a Shelter when the cycle ends, and each of their corpses despawns on the next cycle. They're incapable of travelling through pipes on their own, so this can be achieved by moving their corpses into the Shelter (If Remix is enabled, requires "Vanilla Exploits" to be possible for the listed creatures other than 
Vautours de Miró) or with exploits.
Neurones were also excluded from the limit.