Concept = Islands: A Journey Across the Vast Sea Thread

This is an idea that I have had for a long time now. It is going to be a 2D sandbox game set in an infinite sea. You start off stranded on an island and have to rebuild a ship. Once you rebuild a ship you can sail to other islands and eventually get upgrades like an engine(so you don't have to worry about wind) or a submersible(so you can dive underwater), you can unlock other quadrants(the sea is a co-ordinate grid), and fight the opposing side(When you make a character, you choose Sailors or Pirates). While you are out at sea, you can sail close to a sea monster to battle it or sail onto a deeper area of ocean to dive.
Other Notes
-The Sea will be a top-down view where you sail the ship, while the actual islands will be side scrolling
-The graphics style will be pixelated
-The sea is infinite, but islands are limited size worlds
-Some islands will have volcanoes, but not all. I possibly plan to make it so that volcanoes errupt
-I plan on there being various generated structures

Let me know what you think of this.