Keep in mind the game clock is in GMT ( Greenwich Mean Time ) at Greenwich UK.
Its used as an international standard in radio & science to save confusion.
GMT NEVER changes zones. Only your local time zone can change + or -
1 hr.
For setting GMT you can use any SW radio & get it 24/7 on either WWV or CHU
https://www.nist.gov/pml/time-and-frequency-division/radio-stations/wwv
http://www.nrc-cnrc.gc.ca/eng/services/time/short_wave.html