As a level of a puzzle game could be fine. I know that 3 days is a short period to make a game or a demo, but I dont understand what is the goal of the player. It is true that I knot that I have to enter a code, but maybe with a brief description of the context to have a better idea would help me to rate the game.
On the other hand, I like the music you made and the graphics remember me to Papers, please. Really cool!