I feel like this game would be fun with maybe some eventual multiplayer.
Some weather, temperatures, and day/night cycles would be great. A way to become to hot or freeze because it's too cold. Maybe a bed so you could sleep.
Some way to make the game more difficult, because after a little bit of playing it, you've got everything you need and you're basically living in a mansion.
Maybe some more wildlife perhaps? A fishing net? Maybe even a way to dive down into the ocean and do something. Perhaps ... a way that you could even be rescued if you build a signal or something in time, like a way to beat the game type thing.
And I feel like the biggest thing this game NEEDS, is more resolution. I can barely see anything on the resolution I have to play it on.