As you said, this does look like a prototype, but it is actually pretty functional.
It would be really good if you put upgrade costs under/on the buttons and not in tooltips, so it is possible to see the costs without hovering over each upgrade separately. More description text in general would be good, especially for the combat part of the display: would be good to label your attack charge bar, enemy attack charge bar, and enemy HP; also add the monster descriptions to the area where you choose in which area to fight (something like "Mushroom, 3 HP, reward: 5 food, progress: 0/6").
AttackSpeed says in the tooltip that it needs Gold, but it actually requires Stone.
The boss minigame was nice. Hope to see more progress done on this game in the future!