Having to balance between your health bars and the parasite's health bar is an interesting concept. The water deposits ended up feeling like the bonfires in a Souls game lol. There were a couple times where I was close to the brain but had to run back and was afraid my thirst meter would deplete before I could get back to my "bonfire" to replenish.
I was a bit confused about the win condition--at first I killed the host right away, but didn't immediately realize I'd lost. It would've helped to have a "you lose" screen or something to make this clear.
Great work, and congrats on finishing the jam.