After over 10 hours of playing ThreadSpace Hyperbol I feel ready to slowly post a review here.
First of all, TSHB is a polished game, much more so than any other game I've laid my eyes on yet (barring maybe SPAZ considering it has similarly active developers and good support).
I've encountered a few bugs, but given that I seem to be very alone with those bugs it might be something about my system. I've written in the forums and the dev has replied very fast, for a game with pretty much 8 years on it's back that's really something special.
What about the lack of human players? To be honest, there are a bunch of active players, so it's just about getting on at the same time as those. Just post or look on the forums, add the right persons and you're set to have some fun with human players. Not right any second you'd like to but it's really not that much of an issue. And then there is the hyper hour every saturday, during which the game is freely playable with the demo, and apparently at that time there are a lot more players.
The gameplay itself is really smooth and nice. Very often I have the feeling that certain things in games work wrong or weird, or that this and that is just not really my fault. In TSHB? If I die it's either because I'm facing too many enemies at once or because I make mistakes, it's as simple as that. There are no lethal glitches or the likes and the physics system is very straightforward, reliable and understandable.
The tutorials are also made with great care, they're short, fun, and teach you most though not quite everything you should know. Bonus points for having voices in the tutorials which aren't annoying one bit.
I can recommend getting this game, even if it is 8 years old. I got it vastly reduced myself, and to be honest I wouldn't pay the full price because it'd be more money than I can comfortably spend right now, but the game is worth it.