Soldam (GB) Ultimate Easter Egg Discovered!
Do the "Sound test" cheat at the title screen first (Down, Up, Down, Up, Select, B). Then set the BGM/SE index 02 and press A once. Set BGM/SE index 19 and press A once more. Now input following series of codes. I split the long long code to a shorter fragments to be easier to input: Up, Up, Down, Down, Left, Left, Right, Right, Select, Select, Up, Up, Down, Down, Left, Left, Right, Right, B, B, Up, Down, Left, Right, Select, Up, Down, Left, Right, B, Select, Right, Left, Down, Up, B, Right, Left, Down, Up, Select, Select, Right, Right, Left, Left, Down, Down, Up, Up, B, B, Right, Right, Left, Left, Down, Down, Up, Up and finally press Start. If done right, the screen with some kind of secret information about one of the game programmers will be displayed in the same style as the ending staff roll. Its STAFF roll name is Sakasita "HIROPI" Yutaka. This message name is "KASAHARA HIROPI". Judging from accessing method, this message not intended to be someday revealed to the public.