I have the original of this (the Switch version is a HD remaster) on the GameCube. Back then, it was only available in Japanese and as such the plot, such that it is, made no sense at all. Now, it’s in English! It has made no difference.
Some bad guy has built a drilling themed theme park under which he’s made a giant drill that he intends on using to drill to the planet’s core and destroy the world. But, since Mr Driller and his drilling obsessed friends have all come to DrillLand, they discover it and ostensibly stop him. So why did he build the theme park? Idiot.
Anyway. It plays out with each park attraction being some variation on the Mr Driller formula, and it’s really very good. And very hard. You complete the game by finishing each of the lowest difficulty modes for each attraction (and then stopping the Big Drill), but after the credits and end sequence, you get to play them in harder modes – which generally means digging further. I’ve done a couple of the hardest ones but, well, it’s very hard. As I said.