Some feedback on the gameplay.
I recommend adding some means of having the camera follow the direction the ship is facing. Like when you steer the ship to a certain direction, maybe after a brief delay, the camera follows the ship's direction?
Also, maybe tweak the throttle mechanic. I kept changing the camera completely down when i tried increasing the throttle. Maybe adding an indicator of where the "enemy is detected" will help the player too.
Since there's no map (which i don't think can be included, given the screen space), maybe showing like an arrow, or maybe even highlighting the screen edge to signify where the enemy is.
Or maybe even when taking damage. Helps the player to see where the target is.
My phone was on vibrate, and it kept vibrating whenever I tried moving the joystick. May not be the best choice, since if I keep trying to move, the phone will constantly be vibrating in my hands. In fact, i think it vibrated for every action i did with a tap on the screen, but not sure.
That's what I got for now.