Sometimes I find it hard to visualize a culture where someone will spend 8 hours straight in an internet cafe playing games... But then again maybe I don't have that great an imagination.
Korea definitely has a fighting game scene as well as a rhythm game scene. They cleaned up the KOF tournament at EVO 2012, and they have a few notable Street Fighter IV players as well. A lot of the top Jubeat players hail from Korea, and Konami just recently put beatmania IIDX and Pop'n Music cabs hooked up to eAmuse in a bunch of Korean arcades.