Despite some controversy, survival shooter SCUM is lighting the Steam charts on fire in the few weeks since its Early Access launch. It's already publisher Devolver Digital's biggest launch ever, selling 250,000 copies in its first day. Tens of thousands of players are blasting each other concurrently, but the game and its popularity seem to all have come out of nowhere. So what exactly is SCUM, and what do players find so compelling about it? That's what this article is for.