When you're on Arqade you can switch to Meta by clicking on a item in the Community Bulletin.
Is there a link to switch back to Arqade ? Other than editing the url (removing "meta.") or scroll to the bottom of the page and click "Arqade (gaming)".
You can use the site switcher on the top-right of the page to switch between sites:
Alternatively, the help button has a link as well:
