Challenger

Hidden Message
In Scene 2, press A, B, A, A, B, B, A, A, A, B, A, A, B, B, B, B, A, B, A, B, A, B, B, A, A, B, A, A, A, B, A, B on Controller 1. The message "KIKU MEGU LOVE STORY!" will appear, after which you'll be sent to the title screen.

"KIKU" is short for Kikuta Masaaki (菊田政昭), one of Hudson's programmers. Most games programmed by Masaaki, including Nuts & Milk, Raid on Bungeling Bay, and Binary Land (which has the same "LOVE STORY" message), have secrets or hidden messages.

By the way, writing the sequence as a binary string in which A stands for "0" and B stands for "1" (i.e., "0100 1100 0100 1111 0101 0110 0100 0101") will give you the hex string, which in ASCII means..."LOVE". Clever, isn't it?