Thanks! I'm really glad you liked it :)
I'm sorry about your struggle with the icons e sprites. The pixel art is so small that some times assets blend together. I should have picked slightly different colors for the resource gathering nodes or used a highlight shader.
The upgrades bug was just some bad coding on my part:
if player.iron >= iron_cost: player.iron -= iron_cost if player.grass >= grass_cost: player.grass -= grass_cost if player.sticks >= sticks_cost: player.sticks -= sticks_cost if player.berries >= berries_cost: player.berries -= berries_cost upgrade()