It's an exploration and puzzle game. You explore the world to collect things.
Pikmin 1: you crash land on the planet and have 30 days to collect your spaceship parts before the toxic oxygen kills you.
Pikmin 2: your planet is almost bankrupt so you go back and collect things for money (essentially)
Pikmin 3 idk cause I haven't played it.
But there's a lot of puzzle working, exploration, and combating the hostile wildlife.