Super Mario Odyssey does away with the concept of lives. No, that doesn't mean it's the first Permadeath Mario - quite the opposite in fact. Mario never loses lives in Odyssey, just some of his hard earned cash. A pair of tweets from the game's official Japanese Twitter account lays out how it works.
マリオの体力が0になったり、奈落に落ちると、持っているコインが10枚減ってしまいます。ただし…！いくらミスしてもGAME OVERはありません。 pic.twitter.com/6oEia6LcVrJuly 4, 2017
Translation: When Mario's HP is reduced to zero or he falls off the stage, he loses 10 coins. However, no matter how many times you mess up, you will not get a game over.
ちなみに…！コインが9枚以下の状態からミスしてもGAME OVERにはなりません。安心して探索を楽しんで下さい。July 5, 2017
Translation: By the way! Even if you fall with 9 coins or less, you won't get a game over. Please enjoy exploring without worries.
Ah! Finally, stress-free exploring, free of frustrating consequences like a big, menacing game over screen. I mean… unless you want to buy hats. Coins aren't just for paying to the Reaper for another shot at life, you see. They're also for buying things at in-game shops. And there are a lot of hats (and outfits and souvenirs for Mario's ship) to buy. You can earn different kinds of coins but they're all used for the same thing.
The primary use of hats and clothes is self-evident: lookin' and feelin' good. They also have the secondary benefit of letting Mario access areas that would otherwise be off-limits; for instance, wearing the construction outfit from Super Mario Maker will convince a (rather lax) security guard in New Donk City that you're a building inspector, or keeping him comfortable deep in the wilderness.
Ergo, every 10 coins lost by falling into a pit is a significant step backwards for both Mario's fashion life and world exploration. Sure, it probably won't take you too long to earn back 10 coins, but just imagine how quickly they could melt away when you've got a particularly rough platforming segment to clear… almost makes you wish you could go back to farming green mushrooms, huh?
Check out our central hub for more Super Mario Odyssey info, and watch more than an hour of Super Mario Odyssey in action from E3.