EDIT-2: I finally figured out the code: "0009" WOOT WOOT! I figured something out
This afternoon I was messing around with codes in the setting menu, I already know the 4321 code (blitz) and the 1234 code (Johannes Kristmann, one of the creators)
But I tried out random numbers on the keyboard, and I ended up with a character that had no avatar/art. Stupid me figured that I knew the code, so I tried the 1234 code then back to the code that I had discovered, which I didn't remember correctly, or was more than 4 numbers as to keep it secret?
the numbers were between 5 and 0, I know that this sound dumb, and made up but I'm telling the truth, I'm devoting the rest of my evening to finding this code, from what I can remember it looked like a explorer that was never finished/still being worked on.
If the Devs are reading this, could you please fill me in on it so I don't go crazy/the others don't think I am, of course its a secret for a reason, but I'd love to hear your side on this
So far most of the secret explorers consist of characters that have been designed and requested by our player base that bought the explorer edition over on our homepage. We'll add more custom explorers over time though. I don't want to give away codes as we leave it up to the players if they want to share their own code or not, but I can tell you that all codes are 4 digit long and they can be between 0000 and 9999. 
