The celebrate the upcoming release of the NES Classic Mini (or Nintendo Entertainment System: NES Classic Edition system, if you wish), Nintendo commissioned Japanese writer Akinori Sao with interviewing key staff involved with the console's history.
One of his interview subjects is Yoshio Sakamoto, famous for his work on Metroid, WarioWare, Rhythm Heaven and - most recently - Miitomo. He had only been with Nintendo for three years he developed Balloon Fight, which was ported to the Famicom / NES by none other that Satoru Iwata, future president of the company.
Balloon Trip is a single-player side-scrolling game in Balloon Fight. Apparently, Iwata-san made it in just three days.
Sakamoto: That's right. It came from an inspiration Yokoi-san had. He told us what kind of vision he had for the game and Iwata-san basically made it in three days. About the time the game was reaching completion, Yokoi-san came up to Iwata-san and myself. He and Iwata-san were acquainted by that time, so after a brief greeting he started playing Balloon Trip. And as usual, he played for a long time.
Of course! (laughs)
Sakamoto: Then, after playing through, he told Iwata-san a bunch of things he'd like to have fixed, but they weren't easy fixes. I say this because at the time, programmers would put out on paper what they had programmed and then do corrections while consulting a stack of paper as thick as a phone book.
Those were difficult times.
Sakamoto: Just fixing a few places would take at least an hour, so Yokoi-san must have intended to go back to his desk and have a cup of coffee or something until the revisions were finished. But when he stood up to leave, Iwata-san said, "Just hold on a sec," and began typing away on the keyboard. Then he said, "All done!"
Sakamoto: I was amazed that he could make the revisions so quickly, and even today I remember how Yokoi-san exclaimed, "Already?!"
That's incredible…I'm speechless!
Sakamoto: Iwata-san had memorized the program.
Everyone considered Iwata-san a genius programmer, but hearing that story makes me realize it all over again.
Sakamoto: Yes, it really does.
He also recalls Iwata's story regarding how he and the late, great Gunpei Yokoi met for the first time:
When Balloon Fight was in development, Yokoi-san was the producer and Iwata-san programmed the Famicom/NES version. Do you have any particular memories of those two from that time?
Sakamoto: Yes. I remember two things clearly. One is something I heard from Iwata-san and the other is something I actually saw. I'll start with what Iwata-san told me.
All right, please go ahead.
Sakamoto: When we made Balloon Fight, we had Iwata-san come to Kyoto to do all sorts of work in a room prepared for him at Nintendo.
At the time, I think HAL Laboratory's head office was in Tokyo instead of Yamanashi, so that means you had him come all the way to Kyoto to do his programming work.
Sakamoto: He didn't stay all the time, but he would come every once in a while. He holed up alone in a room and started working, but suddenly a dashing gray-haired gentleman came in and, without saying anything, planted himself in a chair and for a long time played Balloon Fight—which was still under development.
A dashing gray-haired gentleman?
Sakamoto: That was Yokoi-san.
Sakamoto: Iwata-san wasn't sure how to react.
Ah, because Iwata-san didn't know Yokoi-san?
Sakamoto: Right. They weren't acquainted yet. Then, after playing a long time, Yokoi-san told him to fix this and that and then left the room. Iwata-san wondered who that man was, so he later asked us and finally learned it was Yokoi-san. Iwata-san told me that story himself.
So that's what happened.
Sakamoto: Isn't it a neat story?
I love it. It's very much like Yokoi-san to play the game in silence and then point out problems.
Iwata would later become head of HAL in 1993, steering the company away from financial ruin and eventually joined Nintendo in 2000. He succeeded Hiroshi Yamauchi as Nintendo president in 2002 and held the position until his tragic passing in 2015.
The full interview is well worth a read, so make sure you do that.