Thought this was a solid clone Gen!
I also agree with Miles' comment about it feeling a bit slow, so allowing the player to go faster might be a good idea!
Another thing is that in the original game, if you shoot while turning, the missile/bullet will also go in the direction that you are turning. I think having a mechanic like that in your clone might help things feel a bit better. It would also help make "aiming" more interesting in your game!
Had a lot of fun with this one! And I definitely applaud you for making 14 whole rounds as well :)