I have some ideas that would make the game harder and realistic
-The fishing rod requires bait to catch fish because its too easy to get food. Thatch should sometimes come with worms (used for bait).
-When you kill a shark it needs to give 3 pieces of shark meat not 6, again, its too easy to get food. Also, making the growing time for the potatoes would make the game harder, also giving 2 potatoes instead of 3.
-Placing roofs on walls without a pillar needs to work, its logic
-Each time you want to heat up the cooking station and the water purifier you should need 1 plank and 1 scrap
-Later on in the game you could make something that would make your raft move your water. You could explore little sand islands(as big as 4 foundations) that have banana trees that you cut, get bananas, wood, thatch , take their seed and plant banana trees on your raft. Also on islands you can find strawberries