I like the concept and the idea!
The soundtrack is good, maybe the sea storm could be a little bit louder.
The gameplay is easy and simple, but sometimes i don't think my weapons are killing him.
Sometimes the monster oneshots me (i don't know if this is intended).
The game is a little bit too hard, cuz i played it some time and i didnt kill him more than 3 times a game. Maybe consider adding something to restore your health a little bit, maybe a bottle of rum?
The mouse is fixed in the menu, which means you cannot move it - this is a simple fix - if you press escape, the menu activates AND the mouse should be unfixed - you could just add this C# code:
Cursor.lockState = CursorLockMode.None;
Cursor.visible = true;
Overall, a nice game! Thanks for sharing it with us and good luck with it!