I know that it takes a lot of work to produce this game but there a lot of failed details/mistakes:
too much grass makes it laggy
chaotic topology makes it quite painful to play
GUI messages are misplaced
cell locations must make sense (use points of interest)
This will take less than 10% of the work you put in the current version, and even if this was just a test game for learning purposes, i suggest you make these little improvements for the players :)
nice job, I like the atmosphere. I played a lot of these (since I made one myself) and this one feels difference from the others.
Cons are : island too large or player movement too slow; camera position feels like the character is 50cm tall.
Nice little game ! However I feel there should at least be frags & deaths counter. Anyway, nice use of Unity.
How much time did you spent on the making ?