Sadly Jules, there isn't much you can do while actually playing games to lose weight, save running on a treadmill with a TV in front of you. In terms of more pleasurable exercises, sex is a great one. It's a good cardio workout and it tones your entire core and lower body, you'll definitely lose weight if you make love every day.
But if you wanna try something else, try intermittent fasting (it's not for everyone, and it's not a diet. It's just tell you when to eat and when not)
Google it.
Oh and drink **** TONS of water, eat healthy food every day and on Friday, Saturday or Sunday get your cheat meal : Pizza what ever