It can be extremely hard to give up playing computer games. That's why many people never succeed. It's better to try another approach. Try to cut the time you spend behind the computer.
Easiest way to do that is to find some other activities. You need to choose something that will keep your mind occupied. Writing articles or poetry can be good solution. It will certainly keep your mind occupied for longer periods of time. You will also exercise your brain. If you are a student, try to focus on a school a bit more. I know that killing a bunch of enemies is funnier than learning about somebody else who did that in real life. That doesn't change the fact that computer game is only a waste of time. However, the things you learn while studying for school can help you in the future. Sports can also be a great solution. You will become healthier. Sporting will also keep your mind occupied. There are many activities which you can perform as your hobby. They can take a lot of time too. They can also be very demanding on your brain. You should try to find as many activities as possible. You will realize that you spend lesser amount of your time behind the computer. Maybe you will leave it completely after some time. The outcome is up to you. Anyway, this is the easiest way to beat the computer game addiction.