The Galaxian series game Gaplus (known as Galaga 3 in some markets), released in 1984, has an interesting trick involving its high score screen in the Japanese version: If you enter your high score with the initials JNIWAR with your Age as 28 and Blood Type as OO, you’ll receive a Japanese message written in romaji, which translates to:
“You have beaten Gaplus. In commemoration, we send you this message. Send a letter to Kozima at Namco, and he’ll give something to the first 10 respondents. Sorry, but turn off the power now.”
The aforementioned Kozima may be Sing Kozima, who worked on Namco’s Motos the following year. This message seems to be a leftover element from earlier in Gaplus’ development, as the final version of Gaplus cannot be beaten. Perhaps Namco had a contest in store that was rendered moot when the ending was removed? Regardless, this message in inaccessible in international versions of the game.