The mechanic is a really cool idea. I was skeptical at first about it wondering what happens if I lose the ability to go forward (thinking forward was a global upwards), but having the movement turn based solves that problem in an interesting way.
I feel either the player should have been a little faster, the projectiles a little slower, or just less projectiles earlier in the game. The difficulty was weird to me. At first it was really hard but after but on every couple attempts it was for seemingly no reason very easy. Not sure if this was just more or perhaps the way the RNG was set up allowed for very lucky runs or something.
The mines also didn't need to be so hard to see. I didn't even realize they were a thing at first and was very confused and frustrated blowing up. Once I did see them they weren't hard to spot so the lighter color is perhaps unnecessary; the player is going to have difficulty turning around them while trying to avoid bullets and with some of their controls missing anyways, no need for them to be hard to see as well.
The audio was well implemented and the music was neat.
Overall, it was a pretty fun game and a very creative use of the optional theme.
PS dammit Hank!