I like that the title screen lets the player move the boat and practice shooting before the game actually begins. It’s a nice way to learn the controls by trying them out instead of only reading instructions.
I did miss the “Press Space to Start” message at first, even though it is shown at the top of the screen. I think moving it closer to the center and making it gently blink could make the transition into the game much clearer.
I also found the difficulty ramp a little too steep, especially because the control scheme itself takes some time to get used to. Movement and aiming are independent, so even the first enemy requires some adjustment.
The first encounter has only one enemy, which is still manageable while learning the controls. But in the next stage, the number suddenly jumps to four enemies, and I was defeated before I could deal much damage.
Rather than making the enemies much weaker, I think a more gradual difficulty curve could work well. For example, enemy shots could have a slightly longer interval at first, and the number of enemies could increase step by step — 1, then 2, then 3, then 4.
That would keep the challenge while giving the player enough time to become comfortable with the unusual control scheme before the game starts demanding faster reactions.