This code appears to be more of a bug. At the "Game Start" screen press U, D, L, R, R, U, then press (A+B+C). This will make your screen fill with Hex code that overlaps the playscreen during game.
At the "Game Start" screen press U, D, L, R, R, and Up. Then, when you get to the screen that says "New York -- Stage 1", press R or L on the control pad to change your starting level. Once the game starts, you can skip to the end of the stage by pressing START, and on the final stage this will take you to the ending credits.
At the "Game Start" screen press U, D, L, and R. Now you can select the "Training" difficulty setting, which will allow you to continue from where you were killed instead of being sent back to the beginning of a stage. This code also makes the game generally more difficult.
Right after you place a row of columns, press START and you will see the next row that will drop.