Bro playing the comp all the time?

my brother plays the computer like its his life (easy 5-8hrs a day). i need advice, what should i do with him. the solution isnt as simple as "hey tell your parents". my dad lives in another city (b/c of his job) and my mom is sick so there isnt much supervision. however, my parents (when possible) give him the "Responsibility" speech all the time but he doesnt listen. if my parents like force him from the comp. he gets very angry and all hel! breaks loose. he isnt the sociable type so he has very few freinds so he cant really hang out with them all the time. additionally he refuses to play outside. The reason why im doing this now is that when i was cleaning the attic i saw all these "honor roll" principle roll certificates. This kid had an avg of 96 only 3 years ago and is barely ping high school. Please give me any suggestions, they would be greatly appreciated.