Update: Bad news, folks. The beta is over. We'll let you know when the official release pops up! In the mean time, why not explore the developers' website?
Synermous is either a clever statement about the transience of life, the value of relationships and the permanence of one's bad decisions or a delightful experiment with new technologies. I suspect it's both. Most likely both. The developers call Synermous a 'massive anonymous online experience' and, you know what? That's exactly what it is.
Instead of prompting for a name or feeding you a tutorial, Synermous opens with darkness and then a trinity of unexplained words ("Birth. Death. Trace.") The darkness will eventually retreat and you'll be deposited into what appears to be a digital version of the Northern Lights. Your avatar in Synermous is a small white square, tiny and vulnerable looking amidst the shifting colors and the other denizens of this colorful place. The controls are simple: you direct your angular persona by clicking anywhere on the screen. In a manner mildly evocative of thatgamecompany's Journey, your manifestation in this world will occasionally call out: a tiny, radial pulse of sound to intermingle with the ambient music.
Though it begins without much explanation, the rules aren't too difficult to puzzle out: black squares are bad, white squares are good. What's interesting here is that the black squares are not NPCs but are, in fact, 'ghosts' from the past: the leftover echoes of some player's previous explorations. And the white squares? Real players. Not mindless automatons.
I'm going to keep the rest of it under my hat. Part of the appeal of Synermous lies with the joy of discovery; you're not going to like it terribly much if I tell you everything. So, go play it and get yourself some rose hip tea and a complicated vegetarian dish to augment the experience. (Note: this is just a beta and not the real deal.)
Hat tip to @pohungchen