Super Xevious: GAMP no Nazo

Not to be confused with Super Xevious from the Arcades, this Famicom exclusive sequel involves solving riddles to move onto the next stage. If one fails to solve the riddle, the stage repeats until it's solved. There's also a fan-translation in English. It's the Riddle of GAMP!

Secret Password Screen#

Start a new game. Before destroying any enemy on the level, press Start to pause the game. Then press Up, Down, Left, Right, A, B. The Secret Password Screen will appear. Press Left / Right to select a digit, press A / B to select a number. Press Start to play. Levels passwords:

Developer Credits#

The game contains a hidden copyright text encoded with the regular ASCII charset, but shifted down by 128 characters, at 0x19F90:

*Copyright 1986 namco ltd. all rights reserved 
*program checker Haruhisa.udagawa &  Kumi.Hanaoka
watashiwa kumichan ga daisukida!

And also at 0x1FE50:

Haruhisa.udagawa &  Kumi.Hanaoka

The last sentence in the first string means "I love Kumi-chan so much!".