Thank you for the comment! we decided to go the "kirby" route which was easier to balance against. Had we had more time we might have made multiple upgrades possible at the same time; with more of them.
We feel as if we incorporated the theme best explained by one of the first lines of the narration: "The Immune System, a bottomless pit of complexity; though from the view of a cell, life is essentially in 2 Dimensions." We wanted to move away from what we expected a lot of people to do; and tried to add a more creative interpretation of the theme