Community-discovered, not a normal unlock
No official unlock path was found in the Steam store, achievements, or developer announcements reviewed for this page.
Save-editing boundary
Claims involving machine_party_customization.save and active_cosmetic_hat could not be traced to a reliable original community source during this review, so no values or steps are reproduced here.
If you investigate independently, back up the save first and expect version-sensitive behavior.
Frequently asked questions
Is the secret hat an official achievement unlock?
No official achievement or unlock route was found.
Should I edit the save file?
Not from unverified copied instructions. Back up first and require an original current source.