Ms. Pac-Man (NES, Tengen)
This game has a hidden level select.
Tengen's port of Ms. Pac-Man for the NES is, surprisingly, a much more faithful port than Namco's own port, despite being released three years earlier. This particular port was ported to the Genesis in 1991, which was then ported to the SNES in 1996. Port port port.
When the game is paused, input the following button code: A, A, A, B, B, B, Up, Down, Left, Right, A, B, A, B, A, B, Up, Down, Left, Right, B, A, B, A, A, A, Up, Down, Left, Right. When activated, the Select button can be used to instantly skip to the next level. This cheat will also unlock the ability to start a game from a level higher than 7, up to 99.