In 1996, Richard Bartle wrote Hearts, Clubs, Diamonds, Spades: Players Who Suit MUDs, which describes "four approaches to playing MUDs" (1996). This paper became famous, and people used this taxonomy to explain players' motivations in games of all types. For a period of time, the Bartle Test of Gamer Psychology (an online personality quiz sort of thing that assigns you a score on each of the four dimensions, currently available here) was well known among gamers, and it was common to hear people referring to themselves as Diamonds or to speak of spading out some mechanic (i.e. exploring it to figure out how it worked; this usage was common among Kingdom of Loathing players, IIRC).
Today (in 2023), the Bartle Test is no longer as popular, which is well enough, as the four categories Bartle proposed don't seem to match up well to how and why people play (or otherwise interact with) games today. Anyway, the focus of Bartle's paper was balancing the player population of MUDs by encouraging certain kinds of players to join, not explaining why people in general play games in general, so it's not surprising if it doesn't do that well.
Achievers (or Diamonds) want to achieve things in the game. Level up, get rich, beat the bosses.
Explorers (or Spades) want to explore and learn about the game.
Socialisers (or Hearts) just want to interact with other players.
Killers (or Clubs) want to hurt people, and the game is where they do it.