They are all used. Thanks to the 41 great people who didn't post there used codes here. I really enjoyed wasting my time like that. Think I'll do it again for fun.
Honestly you aren't missing much. The game needs a lot of work. It's unpolished and buggy. The level design wasn't perfect either. I was able to skip large portions of many levels due to the fact that you can fall long distances and just spam the jump button to keep from dying.