For instance, when asked by Next-Gen whether Nintendo designed Super Mario Galaxy thinking about the difference between casual gamers and hardcore gamers, Koizumi describes his discussion with Nintendo Designer Shigeru Miyamoto about on this topic.
…we feel that ultimately there's no real difference between the two groups. Games should be something that anyone can play, and if you're doing that correctly then there’s no reason to pay quite so much attention to this idea of a huge divide between hardcore and casual.
Wired talked to Koizumi about how he joined Nintendo after first playing the original Super Mario Bros. at the age of 21 and eventually focused on the topic of story in Nintendo games, which turns out to have been influenced heavily by Koizumi.
For example, I always liked the idea of you coming upon another character and hearing little bits of conversation that slowly begin to reveal different parts of the story… but those are aspects of the games that Miyamoto wasn't nearly as fond of and occasionally didn't like.
Finally, Koizumi talked with Game Daily about where Nintendo's level designers found inspiration: food. Because food can be so visually appealing, a lot of Galaxy's planetoids started out as peanuts and watermelons. Even Super Mario Sunshine was inspired by food.
When I was talking to people about how to create the sludge effect, I always described it in terms of food - like, "Think of this one as covered with chocolate sauce, or this one as a raspberry, or this one as marbled with all different kinds of flavors. And make it like it's sticky and you're walking through it.
If you’re feeling hungry for more, be sure to check out the full interviews from Next-Gen, Wired, and Game Daily.