There's a running gag in some circles of the Old School RuneScape community that Slayer, a skill about hunting down set amounts of different monsters in what some MMOs would consider side quests, is everything. It's a way to train your combat skills, get resources for non-combat skills, and obtain a lot of valuable gear. Now, thanks to a custom companion app created by a self-described hobbyist-turned-professional game dev, Slayer is literally everything in a game mode dubbed SlayerScape.
OSRS is a strong contender for the game, or certainly the MMO, with the most inventive player base, and the SlayerScape series from YouTuber DanPlaysOSRS (or Broxxar on Reddit, where I saw this) is the latest to make that case.
