Nice gameplay concept and excellent polish! Risk/reward choices (launch velocity, "escaping" missiles via edges) feel good, and having the extra chances after splitting is fun too. The audio is well suited to the theme, graphics, & pacing of the gameplay. I also love the addition of the cheat code.
I kinda wish the difficulty ramped a little more slowly, or were a little more configurable, but at the same time, the fairly rapid escalation and quick fail speed feels well paced—the play sessions are bite-sized and exciting. Maybe a "training mode" could be helpful? I'm kinda on the fence.
Some minor issues: I used the web build and had trouble catching the asteroids—even when holding down the button and waiting, it felt like it was casting late or sometimes just missing the frame where the asteroid passed under. But it looks like you've already noted that a circle cast seems like a better approach there. I also had an issue with catching the asteroid on the edge of the frame and not really having enough room on the canvas for it to register my attempts to launch it back towards the center. It'd be nice if there were a little bit of extra buffer space on the edges to handle that, and it'd open up some possibilities to explore some extra visual effects (e.g. when wrapping, or when missiles hit the edge).
Again, those are minor issues—there's a lot of good stuff here. Great work!