Display safety

Changing resolution, refresh rate, window mode or monitor can leave a player with a black screen. The kit protects them:

Confirmation: after a display change, "Keep these display settings?" counts down from 15 seconds. Without Keep, the previous mode comes back by itself.
Crash recovery: the kit notes the pending change in the settings file before applying it. If the game crashes or is closed during the countdown, the next start restores the previous mode.
First launch: the defaults are the mode the game started in, so nothing changes until the player chooses.

The settings file #

Saved as settings.json in Application.persistentDataPath (versioned JSON).
Written safely: a temporary file is written first, and the previous file is kept as settings.json.bak.
A damaged file is replaced by the backup or the defaults; the damaged copy is kept as settings.json.corrupt and one warning is logged.
Start the game with -reset-settings to delete the saved settings (useful for support).

Refresh rates are offered per resolution; a resolution change re-checks the refresh rate.
Exclusive full screen is offered where the platform supports it.
Monitor selection appears only on Windows with two or more monitors.