Looks great. Definitely will play when you’re finished.
Some ideas to keep play feeling fast while movement is slowed.
- As boats can’t move straight sideways, maybe rotate to 45 to move diagonal and 90 when moving horizontal
- Include a slight drag/delay between phases to simulate the turning of the ship
- Have enemies facing horizontal and shooting from cannons on ship side. When they get from one side to the other, have them need to turn around or simple move of screen and reappear going back the other
- Have an enemy type that tries to ram you
- Allow your ship to ram enemies
- Limit your self initially to shooting from side on cannons but have a power up to enable shooting forward with limited ammo
That’s probably more than you wanted idea wise but I hope it helps