Basically a game that is continuously updated with new content. Lots of different models of it from MMOs to Fortnite to Diablo IV. Many of them are free to play with lots of microtransactions. They usually feature things like seasons and battle passes and loot boxes. They’re almost always heavily monetized. The competition in the “genre” is incredibly fierce since most people probably only play a handful of them and friend groups usually all want to be on the same game. It’s very hard to break into. Sony announced that they were making a big investment into the area a few years ago and news has been trickling out since that most of them have been canceled.