Yeah I agree, the boss needs some more TLC. More attack varieties would be fun, potentially a part where it's invincible and you can take care of its goons or take a breather. Overall, I found that the difficulty was on the right track, but it was a bit sporadic. There were moments that were challenging, followed by points where I was just waiting for more enemies to show up. I would recommend making sure there's always at least one enemy onscreen, as that would keep the excitement up (the asteroids idea would also help! [Random idea, maybe you shoot the asteroids to get power ups?]). I appreciate what you did with the control of the rocket being a little delayed, but I think if things were a little faster it would add more intensity and also add a bit more challenge. I would also recommend making the level WAY shorter. I totally understand this is a demo and that will change, but it was a little frustrating how little the progress bar would inch by as time passed. Hope that helps :D
Thanks again for the tips! We just pushed the new update now, new level, new crazy boss fight. The tempo is also way faster than before. I think you'll love it.
I'll try to have more levels done soon as well, considering adding the asteroids next update also many more types of enemies with new shooting styles are coming too.