Ren'Py identifies "devices" (or distinct installations) using this unique string ID.

Ren'Py embeds device- or environment-specific metadata in save files (version, UUID, and sometimes absolute paths). If the runtime detects a mismatch it warns the player to avoid loading incompatible or corrupted saves.

Ren’Py includes a security and stability feature. Each save file is cryptographically tied to:

This prevents:

But it also blocks legitimate save transfers between your own devices.