It is common for MMOG's to have a constant theme, and sometimes having a day/night cycle that doesn't really affect the game. This MMO has real life cycles including a day/night cycle. The virtual planet has the same day time as the earth, so you will be placed in a region of the planet consistent with your region on earth. You could, however, travel to any part of the planet and make a nocturnal or twilight creature.
In this mode, you are able to wander your creature around and do normal things. Everything is real, everything you do is felt by the planet. If you die in this mode, you will have to start a new creature.
Your creature may enter this mode when it is exhausted, when it is hallucinating, or when you make it sleep. If it is hallucinating or exhausted, you will not be able to take it out of this mode. In dream mode, you enter the dream realm. This is the realm of your creature's memory. You may edit anything, move things around, and even play the dream realm offline. While online in the dream realm, skills that you practice will add to your creature's skill levels. You can even store creatures in the dream realm.
You have the option to keep your creature active while you are not playing. If you are very concerned about its wellbeing, you can put it into a phase shift where it will be frozen in time waiting for you to return. If you do choose to keep your creature active, it will use the skills at its disposal to try to survive. It will eat things that you made it eat, it will perform activities that you made it perform, and it may reproduce and die while you are away.