One method is to take the approach of just uninstalling the games and then trying to live with the withdrawal symptoms until you're over it (while working towards new projects). The other method is to do it over a period of time, while also slowly getting rid of all the distractions that get you to play games in the first place.

I find the second method easier to work with, although some are able to just flick an internal switch and stop one fine day. At the same time it's good to start working on your side projects by starting small (extremely small, whatever you're willing to agree with), and then increasing it over a period of time. I've found this method to help. You could start with something as small as just 5 mins of work per day, or a really small task for that day. Once you feel like you're making progress (no matter how small), you'll automatically find the incentive to focus on it more, and spend more time on it.