Dude,sound like he's addicted to online gaming and just goes into his own wee world when playin them. You need to try and have a serious word with him about it.. Next time when he comes over tell him you need to have a word with him and explain how you feel about him always coming over to yours just to use your internet connection, and that you feel that he just using you for it.. Friend shold be able to talk thing out with out falling out..
Hope it all work out well..