My immediate suspician here given that it's an Asian crime was that there was money/gambling involved. Nothing definate mind you, but consider that Asian gamers tend to take a very differant attitude about competitive games than most people outside of Asia (on a lot of levels). Occasionally I've run into articles talking about how there are entire bookeeping operations based around competitive Starcraft, and other games.
Also there has been a lot of discussion about the nature of gaming and Asian attitudes towards it. Simply put Asians see cheating as part of the game, this has been an issue with a lot of games including MMORPGs and online strategy games for example. Leading to the old jokes about how "you don't think a 14 year old American kid can beat a 14 year old Korean kid playing Star Craft do you?" (oftentimes showing two computers running the game side by side, with the korean one so heavily modified it's barely recognizable anymore as the punchline). The kinds of mods used for Starcraft for example involving things like programs that do build queues in an automated fashion, or give far better control over commanding units in the field or whatever else. Usually in many cases involving entire interface overhauls.
What I'm getting at here is that I'd question the accusation of "cheating" as well since a lot of this kind of thing comes down to mod-wars and making or obtaining the best mods is considered part of "playing" apparently.
So while total speculation simply based on the fact that it ended with this kind of violence, I would immediatly suspect a lot of money (for the people involved) was lost to the victim, legally or otherwise, and cheating was an "excuse" to justify stabbing him in the head so as to avoid having to pay. Maybe there was a "no cheats" agreement, but I'd immediatly suspect that this guy simply cheated better than the others did.