FYI everyone! Press the ESC key to open your inventory. You can only use the mouse on the inventory screen, no keyboard navigation.
Very engaging game play loops. I spent much more time than I planned to playing it.
Like others, I was stymied by a few mechanics. However, the controls are limited so after a few minutes of failures I figured out the battle and fishing mechanics. This reminded me of renting NES games and having to figure the game out without the manual. I think this is a fun experience when the interface (i.e. input controls and mechanics) are simple.
I found half a medallion but at some point it disappeared out of my inventory. I did go to a several islands with special features on them (no spoilers) but nothing obviously happened that would indicate that the half-medallion was used.
I had collected 300 gold but, back on the starting island, I could never interact with any of the huts. Nothing happens when pressing the space key. Also, I would also suggest including crosshairs in walk-around mode also so it is clear where you are aiming.
Good fun. I've definitely revisit this game later.