There's many reasons that Ultima is special, from the pants-on-head insanity of the early games to the sandbox nature of the world, where there was technically a plot to follow in a specific order, but no real penalty for deciding balls to it, finding a magic carpet or jumping into a moon-gate and simply getting lost in both the stories and, later on, the ability to do things like bake bread. At one point, albeit patched out, doing so with the blood of a murdered man and feeding it to his grieving son. Or hire a prostitute for a talking mouse. Or find a hundred ways to break the game systems over your knee for fun and profit. Pretty much all of them are included in one of my favourite Lets Play series ever - the adventures of Steve the Druid.