Thank you for taking the time to play it and write all of this out. This is actually the first real feedback I've gotten on the game, so I really appreciate it.
I think I understand what you mean about everything feeling too random. Right now there isn't much structure behind when threats appear, so even though there is technically progression, it probably doesn't feel like you're working through anything. I like your idea of having more recognizable waves or intervals so the player has something to anticipate and work toward instead of it just feeling like things keep appearing forever.
The pacing is something I'm definitely going to work on too. I don't want a run to take a long time before it starts feeling dangerous, especially if that makes someone not want to immediately try another run. I'll experiment with making the asteroids and overall threat level ramp up much faster.
I'm really glad you enjoyed the actual gameplay and that it managed to create some excitement. That means a lot to me, especially this early on. I'll do my best to take your advice and improve those areas. Thanks again for giving it a shot and for being so detailed with the feedback.