As of right now, Crytek is keeping their cards close to the chest as to what the content of the demo might be beyond it being a “combination of [a game and an environment demo].” But it is safe to assume it will be impressive.
Crytek previously showed off a 100 FPS VR demo at GamesCom in August. According the the VRFocus report on the demo, it placed players in a “wooded environment with helicopters flying over,” and was a “linear piece,” meaning the suggestion from Crytek that this will be a combination of a game and an environment demo suggests this might be a new demo.
Even if it is not, attendees should be excited to try out the demo, which was so impressive that according to reports from GamesCom, Palmer Luckey himself didn’t want to take off the HMD and even forgot his phone in the process of leaving (presumably because he was still caught up mentally in the experience).
We will keep you updated with any new information as it happens.