Hmm, while I'm sure Horizonauts will be pretty cool, this game felt quite underwhelming to me and didn't do anything to sell me on it. If I were to sum it up, this game reminds me a lot of those mobile game ads, you know, those minigames that you want to hurry up and skip over so you can get to the game you actually want to play?
That's not to say the game isn't without potential. The art is nice and energetic, and I do like that the game seems to be going for some complex mechanics and enemy design to keep you on your toes. I'm not one to be against endless runners in general, and this could be good.
But right now it just feels incredibly generic without any unique mechanics to set it apart from the crowd, and even worse, it feels very janky and rough, especially with its controls. I couldn't get certain moves like doing a high bounce off of an enemy to happen consistently no matter how hard I tried to determine the right way to hit my inputs. The hitboxes seemed arbitrary at times with me going straight through those grinder enemies without getting hurt. And there were plenty of other weird cases of missed inputs or just weird behavior.
Apart from that, I had some other complaints like how the window to get into the tutorial is timed: why you gotta make learning about the games rules a missable QTE? It seems so backwards: shouldn't it be that it puts you into the tutorial automatically and gives you a button to skip it? That seems like it would be much more intuitive.
You say it's still in alpha/beta and I can believe that: maybe it was just too early to put this out to the public. Best of luck on its development, and best of luck to Horizonauts!