Quick answer
Progress is tied to in-game triggers rather than a documented manual-save-anywhere system. Let the game complete a save transition before quitting. The Steam store does not currently advertise Steam Cloud, so cross-device synchronization should not be assumed.
Version 1.03 save context
The official notes add a trigger after a specific Dormitory door, allow certain triggers to repeat, and list possible fixes for an elevator breaking a save plus other door and progression states. They also warn that starting Chapter 2 directly can affect transferred items.
Safe recovery sequence
- Update to version 1.03 and restart the game.
- Load the newest valid checkpoint without deleting older data.
- Re-enter the preceding area and cross the intended transition once.
- Wait for the save indication to finish before exiting.
- Report the exact chapter, transition, and version if the state still fails.
This guide does not publish an unverified local save-file path. Operating system configuration and later builds can change that location. Before manual file operations, identify the actual folder on the current machine and copy it to a separate backup rather than overwriting it.