Thank you!
Yea I played around with this a bit - mainly I wanted to ensure a player couldn't realistically run forever without getting caught. I came to an approach of spawning more zombies over time, based on the amount of time you've survived. Then, that time counts backwards when you turn to a zombie and the opposite occurs with humans - less spawn as you go. I described this in another comment, but while it works well enough for this jam, I feel this system could be improved.