I'm not the worst game addict, but a great computer addict. For me it is almost a reflex to start my computer early in the day, as I know I never get bored when I'm in front if it. I either play games, listen to music, browse Wikipedia or other web pages, create music with a midi utility... as I say I can never get bored and that is my main issue.
A few advices I can give to reduce your time in front of the computer are as follow :
1- Try not to buy all and every game you might be interested with (this is the advice shaggydaddy also gave). Controlling and forcing you to not go buy games is way easier than resisting playing once you have them installed on your computer. For example, I never buy any of those massive-multiplayer games as I know I'd be addicted with them and could hardly stop paying them.
2- Focus and find advantages not playing constently might bring you. You might already have some in mind if you consider you have an addiction. For me, not playing too much on the computer gives me more time to practice guitar, read books, do some exercises, clean my appartment and have a better insight on my general situation (as my aspie issues can make me really absorbed in computer gaming and I might loose sight of everything else). Once you can come up with a list, playing games might become a little less enjoyable (at least it is for me) as it can bring up some kind of necessary guilt. Also and by the same token, whenever you will not be playing and doing something else might make you feel more comfortable and proud of yourself, rather than being anxious about not playing.
3- Try to break the habit. By this I mean try to think a bit before starting playing : is it the right time to play, is there something else you should do instead, how many time are you going to play? I find these questions useful as they force me to have a more realistic and convenient gaming schedule rather than just sitting in front of a game by reflex and play until I get bored (which can be a very very long time).
Hope I have helped...