I am hope Deimos will respond to (you)
> How do I log into my old pixel nichan account?
You don't. And it's deliberate. Its an anonymous game. Nametag is saved for the session so it's possible to keep track of people within a conversation, but you can't "log in". We are anonymous, after all.
What's the point of pixel count and the milestone badges then? That account lasted a while - as you can see there were 5000 pixels on it over the course of a few months.