3-D Block © 1989 Hwang Shinwei.
Unlicensed port of Blockout.
Re-released on 1990 by RCM Group with a slightly different title screen.
At the title screen, press A, B, Up, Down on controller 1 then press A to increase level number. By default you can select only first 10 levels. With this cheat, you can select any level up to 20.
At the title screen, press A, B, Up, Down on controller 1 then press Select 10 times. The girl's silhouette will change the color and show actual nude picture.