Update#1
Today I've lost a lot of time doing the sea bed, well the seaweeds to be more precise. The Idea was to put everything in a huge sprite and animate all together. Turns out I'm not ready for such a scale so I had to take some steps back, and now I'm a little behind schedule.
Oh right, seaweeds, I hate them. The problem is that I can't animate them in a satisfying way, so I kept banging my head against them in a very unproductive way.
But the game is slowly coming along, I have a double upgrading system in mind, one for the player submarine and one for fishing area.
Upgrading the fishing area means that a greater number and variety of fishes will appear, allowing the player to make more points but at the same time this will attract more humans making the game harder. Meanwhile, upgrading the submarine will lower the difficulty. In order to do both this actions, the player must spend shells (the in-game currency), obtainable saving fishes.
This is what I've put togeter right now, still unsure if the fishing day should end after a timer or after the number of fishes spawned.
Will update again soon!