Mmm. The overpowered characters, the animation, the romantic interest between the two main characters, and the fact that my girlfriend loves it so she forces me to watch it with her. Also, it's an anime about people being trapped within a Virtual Reality Massively Multiplayer Online Role Playing Game (VMMORPG) Whew. Long title. But yeah, so since I'm a gamer, I'm naturally intrigued by the concept. If they die in the game, their virtual reality headset fries their brain with microwave pulses. The psychology of the anime is really interesting. It's not merely a hack and slash anime, it actually goes into the psychological affects such a 'game' would have on people and how they would try to survive.