The engine typically creates a mirrored save system—one folder in the game directory and another in a system-wide "global" folder. Typical Path %APPDATA%/RenPy/game_directory_name macOS ~/Library/RenPy/game_directory_name Linux ~/.renpy/game_directory_name Android
If you want to save content that stays even if the player starts a New Game (like Gallery unlocks, total playtime, or "New Game+" points), use persistent variables.
Use Ren'Py's built-in renpy.random to generate predictable random numbers based on the save timestamp, or use a simple hashing mechanism to detect tampering.