I didn't see an easy way to get to the demo from the game product page, so I'm posting this announcement.
Also I wanted to pass along a short introduction to the demo to let players know what to expect.
In the demo, players must spread "antibodies" (translucent white voxels) throughout a tube-shaped membrane. Once the membrane is teeming with antibodies, it can withstand the eruption of purple Growth a minute later.
You can get the demo here: Indiedb.com