Thank you very much, we are glad you liked it!
As for the theme, our original idea was to incorporate it in the upgrade tree, you should purchase them carefully balancing the greed of the economy branch (that makes you farm faster but also powers up the enemies) and the necessity of energy/movement/combat branch to survive.
We know it's not the best interpretation but we saw some potential of a game like this and as we progressed the development we diverted a bit from the theme, focusing on the gameplay, because we didn't want to get limited by it.