Very interesting game. It's never too many interesting stories about mermaids.
I like that player can choose beetweem 2 girls. And I know that you made this in under 72 hrs. But You could add more choices and maybe more endings. You know, to make it a bit more intersting.
The story is very simple and a bit liner. You could make it longer and more complicated. And some CGs would be great. But it's still good game.
I like the artstyle. Good sprites, Music and backgrounds are not bad.