Remix

Rain World: Remix, game version 1.9, is the current major game update, released for free alongside the Downpour DLC. It adds a native mod menu that can be used to enable new official and unofficial 'modded' content. The official mods are:
 * Dev Tools
 * Rain World Remix
 * More Slugcats
 * Jolly Co-Op
 * Expedition

Player-developed mods can be uploaded to the Steam Workshop via the upload-arrow button in the mod menu. Uploaded mods can be downloaded by subscribing in the Steam Workshop, after which they can be activated in-game via the Remix menu. Some mods require game relaunch on activation.

Mods can also be manually downloaded by placing the relevant folder in the mods folder under StreamingAssets, after which they are also accessible via the Remix menu.

Steam store description

 * Uncover the most popular mods from the thriving modding community with Steam Workshop Support.
 * Toggle new features and comprehensive customization options in Remix to suit your individual needs.
 * Learn new tips and tricks with updated tutorial messages to help players understand Rain World's intricate ecosystem.
 * Control your unique campaign with accessibility, speedrun, and difficulty options sculpted to your particular taste and style.

Rain World Remix
Rain World Remix contains many options to customize the game experience, including quality-of-life, difficulty, speedrun and 'vanilla reversion'. These are organized under three separate tabs.

Presets
''The options below can be used to quickly reset all settings to preset values. These are recommended starting points for different playstyles.''
 * Remix: Standard Remix settings. Many mechanical tweaks that may mix up the way the game is experienced.
 * Classic: Similar to the original Rain World experience, but with a few quality of life settings enabled.
 * Relaxed: Settings designed to make the game significantly easier, but may weaken the overall game experience.

HUD
[*] If the game consistently loads quickly, these may never show up. [†] These do not show up in More Slugcats campaigns.
 * Speedrun timer: Your total playtime for a character will always be visible as a UI element in-game during campaigns.
 * Hide rain timer in safe areas: Hide the remaining cycle time while in maps that are safe from the rain.
 * Loading screen tips: Periodically shows tips and tutorials during the loading screen between cycles.[*]
 * Extra tutorials: Introduces a few in-game tutorial messages for certain mechanics and scenarios.[†]
 * Stronger bottomless pit indicators: Makes the death gradient on bottomless pits more visible.
 * Show underwater shortcuts: Prevents underwater shortcut symbols from being obscured by the water layer.
 * Visual breath meter: Show a visual indicator on the UI of your remaining breath time. (This is visually similar to Saint's warmth meter)
 * Slug senses: Show icons of nearby creatures on the minimap. (Dead creatures show as smaller, lopsided icons)
 * Rain timer tick-tock: The rain timer makes a tick-tock noise while the UI is visible.
 * Fast map reveal: Increases the speed that the minimap reveals itself.
 * Threat music visual pulse: Shows a visual pulse on screen when threats are nearby. (This pulse is red and increases in size according to severity of threat)

Remix
[*] Even if this setting is disabled, can pull spears out of walls.
 * Additional voices: All lizard breeds have unique sound effects and voices.
 * Vulnerable : Jellyfish are vulnerable to being stabbed. (They die)
 * New dynamic difficulty: Dynamic difficulty is influenced by number of regions visited more than number of cycles survived.
 * Passage progress without Survivor: Allows certain passages to gain progress even before the Survivor passage has been achieved.
 * Increased stun times: Increases the time that rocks and snail pops can cause some creatures to be stunned for.
 * Extra throwing trajectories: Gives additional options for the direction and ways that objects can be thrown in certain circumstances.
 * Pull s from walls: Gives the player the ability to dislodge spears that are embedded in walls[*].
 * Alpha reds: s have a tongue and can snap spears in half with their bite.
 * Item stems in Sandbox: Items that typically attach to the terrain with a stem will spawn with their stems when placed in Sandbox mode.
 * Arena creatures cannot flee: Prevents injured creatures from fleeing to dens in arena mode.

Legacy

 * Vanilla exploits: Advantageous glitches and speedrunner exploits are made available to use again with this option.
 * Legacy tongue controls: Use the throw button to activate tongue controls rather than the jump button[*].
 * Wall pouncing: Enable the wall pounce mechanic.

[*] Affects, s, and (in Safari mode)

Quality of Life
[*] Key items include colored pearls and story objects. [†] Sometimes this causes items to spawn in unreachable locations. If this happens, certain key items can be spawned using Dev Tools.
 * Faster opening
 * Quieter gates/shelters: Reduces the volume for the sound effects of gates and shelters opening.
 * Reduce screen shaking: Removes visual effects that cause the screen to shake.
 * Stronger climbing grip: Prevents falling off poles when throwing objects.
 * Breath time leniency: Increases the amount of time before you are forced to come up for air while drowning.
 * item protection: Prevents Jetfish from being able to knock items out of your hands.
 * Key item tracking: Key items are tracked on the map and will respawn on subsequent cycles if they are lost, at the location they were lost[*][†].
 * Key items on Passage: Passages bring all key items in a shelter with you to the new destination, rather than just the stomach item.
 * kill squad leniency: Gives a grace period on cycle start and region entry before Scavenger kill squads can attack you.
 * Tweaked behavior: Adjusts deer behavior and adds additional mechanics to influence their actions. Wiggling around may startle this creature.
 * No Hunter auto-grabbing: Stop Hunter from automatically grabbing Batflies with a free hand.
 * No stealing back-spear: Stops Scavengers from being able to steal the  off Hunter's back.

Minor Assist

 * extended breath: Increases Monk breath from 0.83x to 1.25x standard.
 * Monk extra light assistance: Increases the radius of Monk's hologram light in pitch-black areas.
 * Wiggle out of grasps: Gives a chance of escaping from different grasps by rapidly wiggling with the movement buttons.
 * No randomized cycle durations: All cycles will have the same duration, and will always use the longest duration possible.
 * pipe protection: Centipedes will release you if you go through a pipe while you are grabbed by one.

Major Assist

 * No swim boost penalty: Swim boosting will not consume additional breath time.
 * Cycles: Changes the number of cycles Hunter starts with in their campaign.
 * Hunter Bonus Cycles: Changes the number of bonus cycles Hunter can receive during their campaign.
 * Slow Motion Factor: Reduces the overall game speed to assist with reaction times.
 * -style gates for all campaigns: For all campaigns, gates will remain open permanently after passing through them once.
 * Disable all Karma requirements: Allow passing any gate for free, regardless of your current Karma level.
 * Rain Timer Multiplier: Multiplies the total duration of the rain timer by this amount.

Jolly Co-Op
Main article: Jolly Co-Op

Expedition
Main article: Expedition

More Slugcats
Main article: Downpour

Gameplay Assists

 * Disable shelter failures: Prevents the chance of waking up early before the rain has stopped.
 * Disable precycle flooding: Prevents the chance of a region being flooded during a shelter failure scenario.
 * corpses have max Karma: If enabled, all Scavenger corpses in Artificer's campaign always have the maximum possible Karma level.
 * Lossless Scavenger corpses: If enabled, Scavenger corpses in Artificer's campaign don't lose Karma after each cycle. This option significantly decreases the difficulty of Artificer's campaign. The intended gameplay loop is to have to actively hunt fresh corpses. It is recommended you only use this as a last resort. Are you sure you want to disable this mechanic?
 * Artificer Explosion Capacity: The maximum number of subsequent explosion actions Artificer can perform before dying.

Cheats
''This menu contains cheats to unlock content early. It is not recommended to use them on a first playthrough. Are you sure you want to continue?'' ''The following cheats unlock content you would normally obtain via finding unlock tokens. Are you sure you want to continue?'' ''The following cheats contain spoilers. Are you sure you want to view these?''
 * Unlock all campaigns: Normally requires completing previous campaigns to unlock.
 * Unlock all arena characters: Normally requires finding Green unlock tokens in the campaign maps.
 * Unlock all arenas: Normally requires finding Orange unlock tokens in the campaign maps.
 * Unlock all sandbox creatures: Normally requires finding Blue unlock tokens in the campaign maps.
 * Unlock all sandbox items: Normally requires finding Blue unlock tokens in the campaign maps.
 * Unlock all safari regions: Normally requires finding Red unlock tokens in the campaign maps.
 * Unlock all challenges: Normally requires completing campaigns and clearing previous challenges.
 * Unlock all collections: Normally requires delivering pearls and finding broadcast tokens in the campaign maps.
 * Unlock the gate: Normally requires completing Gourmand's campaign.
 * Unlock s : Normally requires completing Gourmand's food tracker.
 * Unlock Developer Commentary mode: Normally requires completing all Challenge Mode challenges.

Dev Tools
Main article: https://rainworldmodding.miraheze.org/wiki/Dev_Tools 

Spawning story items
At the moment, items spawned in this manner are not tracked as key items. 5: Spearmaster 6: Hunter 7: