I get that all the time.
It's called discipline and knowing where your priorities are. What's more important: your writing or those video games?
Sometimes games will win out. That's okay. Well, unless you're on a deadline, in which case throw the damn games into the incinerator and plank your ass in the chair.
Or maybe just store the games in a hard-to-access place. They're too expensive to throw in the fire.
Hell, sometimes other, more pressing things win out. It's life. Again, not a big deal unless you're on deadline, in which case you'll have to figure out how to make it work.
Set yourself a daily word goal and force yourself to meet it before you can do anything else. Make a pleasant ritual out of it. For example, if you start associating writing time as a relaxing time with tea, soft music, and your imagination, you'll be more likely to want to do it. This is especially true if you have a stressful, fast-paced life.