Is there just one theme?
Yes, all locations all over the world share the same theme for the jam.
I want to know the theme!
For the usual in person GGJ the theme is announced at each local jam site after 17:00 local time on Friday. Time zones from New Zealand to Hawaii are all participating.
For GGJ 2024 we will be announcing the theme globally at the same time on 20 January between 10am-11am Pacific on twitch.tv/globalgamejam
For themes from past years, see the Global Game Jam® History.