Here’s an excerpt from a 2001 interview with Koji Kondo, it’s from a Japanese book series called “Game Maestro” this one being from vol. 3 of the series.
GM: Being in college can really broaden your horizons, especially when you include the extra-curricular activities. Did you join a band, or any other artistic groups?
Kondo: I did. It was just an amateur band, formed with other students from the college. The sound was fusion, but closer to rock. We did covers of fusion songs from Casiopeia and Naniwa Express. I played keyboards.
GM: I have to admit I’m having a hard time picturing how you got from there to Nintendo… (laughs)
Kondo: At the school, companies would put up recruitment ads for new positions they were hiring for. That was actually the first year Nintendo started hiring for dedicated sound staff. My friend saw the ad first, and he told me about it. “Kondo, this looks like it could be a good fit for you.” I wholeheartedly agreed: “This is perfect for me!” In fact, Nintendo was the only company I applied to.
GM: It seems to me that during the Famicom era, the composers and the game developers worked together in unison. Did you use in-game screenshots and/or footage as a reference when you composed?
Kondo: We did, yeah. In Mario, the first visuals that were completed had Mario running through an open grassy field. At first I added some very light, airy music to that—but it didn’t fit at all. (laughs) Everyone disliked it, and the tune wasn’t very interesting either.
So I went back to the drawing board, and tried to write something with more emphatic rhythm, using that little hi-hat beat as the basis. Then, I added a chord riff using the open voicing technique I mentioned. Working with that chord progression, I created a bunch of melodic variations, and selected the best one for the final version.
it’s pretty lengthly so be sure to check out the full interview linked below.