What you are dealing with is a “process addiction.” Gambling, fluther internet use, and shopping are also process addictions. Similar to substance abuse, your brain is seeking a “fix” every time you play, and it works because you get that fix for very little effort. Another characteristic you may be familiar with is that when you have time on your hands, and you haven’t already decided to play, you may feel at a loss for what to do with yourself.
With due respect to the folks above, I don’t believe choosing to limit your time is a realistic option, because my guess is you may say you’re going to play for 1/2 hour but before you know it it’s 4 hours and you’re still not quite done.
Assuming you’re not going to quit cold turkey, here’s what I’d do (and in some ways am in the process of doing for myself):
1. Don’t buy any new games. Don’t read any more game reviews. Don’t browse games at the store.
2. Look at your collection. Write down the number of hours you think it will take to finish each game. Decide whether there are any games that aren’t going to be worth finishing and get rid of them. Don’t trade them in for credit, either. Just get rid of them and get cash if you trade them in. The difference in the dollar amount isn’t significant compared to clearing things out.
3. From now on, concentrate on simply becoming aware of the parameters of your behavior without judging or berating yourself. Keep in mind how many “total hours” you’ll need to finish the rest of your games. Work on becoming an expert on your habits. Keep track of how much you play (or shop if you can’t follow the suggestion above) each day but don’t be judgmental, just be accurate. Try to catch the urge to play coming on and observe what’s going on in your head. What thoughts are you having that are leading you to want to play? Simply becoming an observer of yourself (similar to zooming out to third person view in an FPS) will eventually slow down those “trigger” moments enough for you to gain an awareness of what your thought process is before you slip into a video game coma, and that awareness will eventually enable you to choose a response to those thoughts other than gaming.
4. I’m guessing there are other things you feel you should be doing. If you’re in a deep enough hole, tackling those “good” things can be incredibly overwhelming, panic inducing and can easily trigger the need to cool the brain circuits with another 4 hours of game playing. To avoid this, take on those good things with really small steps. In other answers, I’ve cited this example. If your goal is to exercise, make it a point to just drive by a local gym every day. No more, no less. From there, move on to pulling into the parking lot and sitting there for five minutes every day. No more, no less. Write down other things you want to do for yourself and ask, “what is the most miniscule step I can comfortably take in those directions?” Pick just one thing if more than one thing is too overwhelming. The key, though, is to remain persistent with your effort, even if it is small. Success breeds success, and over time you’ll be comfortably and habitually doing things other than video games that make you feel better.
So, sorry for the longwinded answer, but my personal experience with this has been a “knowledge is power” kind of dynamic.
Also, this is something that a decent cognitive behavioral therapist can help you with if you want to go that route. You’ll just need to find someone who recognizes video games as a potential addiction.