A Mario game wouldn't be a Mario game without series creator Shigeru Miyamoto's name stamped on it.
And although Miyamoto has says the project started off with very little involvement from him at all, he joined the team later on to make sure they got the essences of Mario right.
"I've made the Mario series alongside Takashi Tezuka, and especially I tend to be the main person in the 3D games. With those titles, I've been working alongside the producer Yoshiaki Koizumi for a pretty long time, so 3D Land is being made with him overseeing a group of younger directors," he told Famitsu (via 1Up).
"I kept my distance from the project at first, but became more deeply involved midway -- I don't think it'd be satisfying as a Mario game to everyone unless I made myself known on the little details."
He goes on to describe the nuances that he personally tweaks to make Mario "satisfying", saying that it's down to things like "how the enemies in Mario should be, or what the music should sound like," or "how much acceleration Mario should have in order for his jumping to feel really good and Mario-like."
He added, with table-upending authority: "It's hard to put into simple terms, but it's something that I really have to be looking at or else it won't happen.
"... I helped fine-tune the numbers behind all of that; it was a really fun part of development."