Anonymous until the end
You're a codename and an abstract mark, like CrimsonFox or PaleHeron, to four or five strangers. No profiles, no DMs. Identities unlock only at the reveal.
The Unread
Read one book with a circle of strangers.
Anonymous until the last page. Then everything opens at once.
Chapter Lock
The next checkpoint opens only when everyone has finished this one and left a mark on it. You move through the book together, or not at all.
The Time Capsule
You can't read anyone's notes for a chapter you haven't reached. Reach it, and their thoughts, written before they knew what you know, open all at once.
The Reveal
Finish the book and the circle opens: names, a yearbook of your best moments, your reading history, and a stitched commentary track of the whole read.