No levels. No classes.
You get better at what you do. Swing a sword and your sword skill goes up. Cast fire and your fire gets stronger. Your character is whatever you spent your time on.
GIF: the masteries panel going up after a fight
Animals live their own lives
Wolves hunt deer. Some creatures only come out at night. They listen as well as look, so making noise can bring something to you.
GIF: a wolf chasing a deer at dusk
Some ruins need friends
Under the ground are the ruins of an old city. Some floors only open when enough people stand on the plates at once, and some guardians are too strong for one person.
Screenshot: a group of players on pressure plates underground
The world changes
Trees burn down. Rivers freeze, and you can walk across them. What you change above ground stays changed.
GIF: fire spreading through a line of trees
Phone or computer
It runs in the browser. Same world, same people, whichever you pick up. Start on a laptop and carry on from your phone.
Photo: the same character on a phone and a laptop
The story
A people called the Arcane learned to command nature by writing on stones. Twelve of them tried a stone meant to open a door to another world. It joined the two worlds into one instead, and what lived on the other side came through.
Three survived. Garius froze their city in time, so every sixty days it goes back to how it was. Dieter made new people, us, who remember what happens. Holleg turned himself into forty metres of earth and buried it all.
People still call the ground Holleg. You wake up in the one room left near the surface, where Dieter is writing the story on the wall.
Pictures
Screenshot: a town by day
Screenshot: a cave by torchlight
Screenshot: casting a stone
Screenshot: a fight
Screenshot: a shop
Screenshot: night falling over a field