Advanced Dungeons & Dragons: Eye of the Beholder (SNES)

Palette Editor
The Pro Action Replay code enables a palette editor which can be accessed in game. Press Select once during gameplay to edit the current wall palette, twice to edit the current monster palette, and again to return to the game.

Press Left/Right to select an individual color within the palette, and Up/Down while holding A, X, or Y to edit the selected color.

In addition to editing palettes, pressing Start while the palette editor is open will skip through dungeons.

Interestingly, right after the code which sets RAM address to zero at the title screen, the game checks controller 1 to see if L+R+B+Select are being held down at the same time. This combination no longer does anything, but it may have originally had the same effect as the above PAR code.

More specifically, the code branches forward if the aforementioned four buttons aren't held down, but the branch distance is zero bytes (most likely due to some important code being deleted), meaning the game behaves the same way regardless of button input.