You figured it out just fine. Chebastian's game is a not-so-subtle commentary on the limitations of hardware (and, perhaps, indeed, about our limitations as human beings).
You see, the GameBoy is a fully-featured handheld console: In addition to the d-pad and start / select buttons, it also has an A and a B button.
Sadly, however, the GameBoy has no Y button. So you can never be a better person.