The demo contains a very small map that runs a single rescue mission.  You can rescue up to four people from the nephilim giants.  Depending on how well you do in the mission, you get four of the magic sigils of creation as you rescue people, and a random choice between two other letters.  Thus, the demo allows collecting up to 6 out of the 22 sigils.  There is also a small pond with fish to test out the swimming mechanics.