This is one of those brilliant ideas that you feel sorry that you didn't come up with yourself. I have much to say about it, but I'll limit myself with several short theses:
1. illusion of multiplayer. It reminded us that level with fake messages from players in the Beginners Guide. The illusion was so convincing at the start, that I totally forgot that I was actually playing a standalone copy on my computer.
2. space AND time! Even after several minutes, new guys kept appearing. Just thinking about how much content is spread across this massive space made me dizzy, but then I realized that it's also spread across time... man this game is rich!
3. non-linear storytelling with strikingly effective direction. We started exploring aimlessly, but the more we wandered off the center, the less chaotic and random new stories felt. We ended up running to the x:-1000, y:-1000 pint, and back to the center, and our experience never felt boring or empty.
4. whenever I went in this white void, I never felt alone. This was a pleasant feeling, quite difficult to describe. Probably, what I felt was trust in the author and in the sincerity of their intention to guide me and say something meaningful. Thank you for that!
5. laconic style, fitting sound and music design, etc. They've set the right tone and removed all distractions.
This was great. Plain and simple. You have our most sincere gratitude for making this game and sharing it with us.