You should be extremely careful as to who you op on your channel. With a network like GamesNET I am extremely skeptical to believe that he opped himself without you giving him access to do so. You must have shared your password with him if none of your commands work now, as he's probably removed your access to the channel. If you didn't share it then it was probably very easily guessable.
In my experience, network administration tend to not help people very much with these problems, mainly because there's no proof that you ever did own the channel once he's set himself as owner, and secondly because you should be careful with all of your passwords. The amount of cases of "friends" taking over channels is ridiculous.
Also, remember that we help with mIRC, not particularly specific network issues - we have *no* authority or power to do anything about it and have no more trust from opers than anyone else. The network will have it's own oper policy on these issues, but usually they are very cautious which leads to little being done.
That said, I'm sorry if you've lost your channel, I'm sure it's a pain in the bum and detracts from the enjoyment of IRC. Still, he can't take your ability to chat or make friends away, so happy chattin'