I don't think one can really consider the explosion of Wordle to be a "pure" game hit, as it was somewhat tied into Twitter's meme distribution engine.
I think a more illuminating case study would be something like that bygone summer everyone was suddenly consumed with conquering Desktop Tower Defense. And the "kernel" of consumption was the shared novelty: "hey has anyone figured out a strategy to defeat the final wave of mega-flyers in level 20?"