This premise of a flooded world is a great fit for the theme. Really impressive that you created such a huge world and also polished the charater animations pretty well in that short time.
Only problem was, that it actually nearly was "too big". Just saw in your description, there are "secrets, puzzles and more". I only found exactly 1 achievement so far and this NPC seems to want to tell me something, but i don't get it :-D
Maybe a little guide or so would have been extremely helpful for gameplay.
But nevertheless, that would be probably hard to also add within on week, so all in all a very impressive entry. Great job, hope you'll continue on it, it definitely has potential.