RimWorld makes the file format comparatively transparent—.rws saves are XML—but that does not make them context-free. A colony serializes references to the game version, DLC, mods, world objects, pawns, maps, and many definitions supplied by the active content set. SaveEditor therefore treats a proper backup as the .rws file plus environment notes. This is especially important before removing a mod or upgrading a heavily modded colony, because an XML parser succeeding does not prove that RimWorld can reconstruct every referenced definition.
Known RimWorld save-file structure
The researched filename or folder pattern is *.rws; manual names plus Autosave-* records.. File-extension context: .rws The documented format notes are: RimWorld saves are XML-based .rws files and embed world/colony state plus references to active DLC/mod content. The game can show the save-data location from its settings UI.
Why an extension is not enough
A save filename can identify a likely container, but it does not prove the internal schema, game version, checksum rules, encryption state, or editability. A .rws file can be structurally valid XML yet incompatible with a different mod set or game version. Missing definitions are a compatibility problem, not automatically file corruption. SaveEditor therefore separates file identification from Tool compatibility and only labels a game-specific Tool Verified when its exact profile/version evidence passes the runtime gate.
Where the format is stored
PC save locations: Windows: %USERPROFILE%AppDataLocalLowLudeon StudiosRimWorld by Ludeon StudiosSaves. Storefront context: Steam, GOG, Epic Games Launcher. The save file is human-readable XML, but it is highly version/mod dependent. Editing XML without understanding cross-references can create a loadable-looking file that fails later. This matters because two releases can use different containers or companion files even when the visible slot name is similar.
Back up before inspecting or editing
Back up the entire Saves folder and also record the RimWorld version, DLC set, and mod list/load order that produced an important colony. A read-only viewer is lower risk than a writer, but the live save should still be copied first. Cloud context also matters: Steam Cloud is commonly used; the official/community wiki documents platform-specific save directories. Keep the original bytes available so any experiment can be reversed without relying on a cloud service or automatic backup.
What this reference does not claim
This page does not infer an undocumented checksum algorithm, encryption key, compression layer, or cross-store conversion from the file extension. Troubleshooting evidence: If a colony fails after an update or mod change, restore the save and matching mod environment together. Use the in-game “Show” save-data-location action when uncertain about the active folder. Those questions require a verified parser/profile or a game-specific source, not a generic format guess.
Verification context: Reviewed against the current RimWorld Wiki Save file documentation and current PC save-location conventions.