Hi, i linke the game and i hope that i can give some good ideas.
the game is to easy at the moment on hard
1. There are too little stuff.
if you find nails you can craft all stuff
2. more sharks at islands will make it harder. one shark is too easy if you know how to attac him.
if there are more sharks -> bigger bait for 2 sharks or more crafted with the otther big fishes?
3. use the clock to see different seasons. At winter you cant plant crops or fishing. so you must stock your food.
4. you can find the blueprints in a box on a raft with pirats or so
pirats try to board your raft
5. a steering wheel that you can turn your raft to sail straight and dont at teh side
6. a storm damage the raft
7. a tool to climb on islands
8. you need the feather for arrows
9. elixir / bandage to heal or you heal very slowly
i hope my english isnt to bad that you know what i mean ;)