Well, it is RPG sandbox. Pretty good mechanics, pretty challenging in some aspects and, for me at least, pretty immersive. Really big choice of things to do: fighting, crafting, building, exploration, research... You are free in this world to do anything, but only if you can survive. And it really creates that motive for action, not that "go from point A to point B and kill 10 bears to collect bear noses, then go back" thing. Runs on Wine perfectly btw.