cyc is a private callboard for a single theatrical production — its cast and crew, its run, and the record it leaves behind. It is not a social network: there are no strangers in it, no follower counts, and no advertising.
A company uses it for the length of one run. When the run closes, the show wraps and everything in it freezes into a keepsake.
cyc is an iOS app. You join a specific production with an invite from someone already in it — there is no public sign-up to a company you are not part of.