Bsides is a little NES game by HypnZA. Users got a “.bin” file and had to figure out it was a NES rom, run it, figure out the clue about a code being a Game Genie (and/or figure out what a Game Genie is and how to enter the code), before submitting their code to solve the challenge (each user got a unique “.bin” file with a unique code).

http://forums.nesdev.com/viewtopic.php?f=22&t=15196