How should we break ties when there are the same number of 1s and 2s?
The cell stays the same if there aren't enough neighbors to overpopulate it ('kill it') or to 'give birth'. (If there are enough of both neighbors to 'give birth', the total will always be overpopulated.)
One piece that I missed was that I had assumed that the cell need to be dead in order to 'give birth'. That's not the case. Cells can change species even if they are already alive.
@brad Thanks for the advice. Hard to tell that from the directions.
Updated directions with example.