My Advice...don't get married. It's a trap.
What happens when you get married:
Are you actually married, or are you just saying what sounds like might happen?
If you have a good relationship, the opposite can also be true.
1. Sex stops
2. She get's fat (probably you too)
Let me rephrase that for ya: Sex stops because you both got fat and can't be bothered.
My wife is in better shape than when I first met her because we've worked together to get her out of jobs that have excessive hours so that she can go to Yoga and other things to take care of herself more.
Sex is a two way street, if you are appealing to her, she will be just as interested as before. It takes work, you have to keep things fresh, everyone gets tired of eating the same thing all the time (puns intended).
3. All your money starts disappearing for no apparent reason.
Money should be clear and open, otherwise there will be doubts or disputes or just unspoken stress. However, yes, there are a lot of expenses that you might not have had when you were living in your mom's basement. Take some time to help with budgeting and understand where the money is going.
4. You will be surrounded by strange and insufferable relatives from some place you have never heard of.
I rarely see her relatives, even though we are in the same city as her parents. But, I get along just great with her family, either way, and I see just enough of them to keep it that way. If you are a good sport about this, it will generally help to keep her happy (if she likes to see family frequently). Just have a reasonable discussion if it becomes too much.
5. You will get to drive the old car.
If driving the old car makes any difference to you, then find an old car that you like.
6. Gaming did you say? That won't last long. "I can't believe you are going to play on the computer AGAIN. You just played last week!"
Just be clear about your priorities and make compromises that are acceptable to both people. Living together before getting married can help a lot in this area.
7. She will start asking you if she looks fat, despite the fact she is perfectly aware of #2
If she is fat, then figure out how to inspire her to get back into shape. It may involve you needing to get into shape, changing your diet, or doing things that she should be doing. Moobs may be par for course, but loosing them would be healthy for you in the long run.
8. She won't cook (See #1) and she won't be able to make a decent dinner.
If you know how to cook, then teach her. If neither of you know how to cook (because your mom did it for you each day), then learn together. It is OK to grow together and do things together when you are married. My wife barely knew how to burn eggs when I first met her, now she can generally make most anything and not burn, over-salt, or generally bung it up. It was an opportunity for us to spend time together and I was able to teach her something I enjoy.
9. You will have to leave the house when her literary friends come over to discuss the life analogies in some gay French author's book.
Tit for tat, boys night out, no problem.
10. LAN parties? No Fucking Way in her house!
This gets back to establishing priorities, a relationship is a two-way give and take. You should still be able to do what is important to you. Again, I would highly recommend living together before hand to really get this sort of thing established.
The good things about marriage are that it gives you a partner in life. Someone that you can rely on to get your back. When things don't work out, you know that there is someone that will understand.
If you don't feel like getting married will actually benefit both of you, then think twice about doing it.