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
NOTE: Version 1.1 of the demo, which includes visual tutorial screens and an additional two levels, has been posted here:
Indiedb.com
I'll create an official news item once v 1.1 of the game goes live, too.