I have (most of) the power

Counting Super Mario Odyssey's power moons is a little complicated. For one thing, some of the collectible moons are actually triple moons that increment the counter on your spaceship by 3; but they still only count as one in the list of collectibles.

For another thing, you can use gold coins to buy an infinite amount of moons. So... huh.

At any rate, there are 836 collectible moons - not counting triples! - and I got 816 of them. The majority of those, I even got without help from the interweb! And the game was really most fun when I was just wandering around a kingdom, looking for things I'd missed.

The 20 moons I've got left are from challenges that I'm deeming too fucking hard, like footraces that require mastery of difficult shortcut-enabling jumps, or the final level that doesn't have any checkpoints.

And I collected all the purple coins for special outfits, which really seems like the most important in-game accomplishment.

Yeah. Mario Odyssey is pretty awesome.