Honestly a very intriguing concept and well executed gameplay; the sound effect detail when someone dies is mildly haunting, and I liked the details of health being visible from the shift in skin color; one thing I had problems w/ was when there is a clump of skulls, it just a block of death which can't be passed w/o losing; two things I would've like to have is an indicator that you've already infected someone (without having to hover over them to check), and in general more UI (like being able to replay w/o refreshing, etc.)
Overall you did a good job and I had fun