In the next few days I want to start a gaming network.
Now I have written everything by myself and I am wondering about legal issues.
For example: Payment, User-agreement, TOS?
I currently live in Germany, do I really need to hire a lawyer before I can publish my gaming network?
What alternatives do I have?
You don't specify, but it's possible based on your industry that you'll have additional issues. Gaming (that is, connected to gambling and games of chance) has rather significant legal issues. If you are operating an unlicensed site, then you may have issues with payment processors. Licensed, you'll have to have a lawyer (been there, done that - you don't really want to tackle that on your own).
No, you don't need a lawyer. You will have to do some other things first, like launching your service and getting people to use it.
I have used a low-cost legal service in the U.S. to handle my legal issues. Mostly this has been asking many questions and being careful not to do things that create legal problems. For example, you should have a terms of service that tells people they are using the service at their own risk.
I would definitely have a lawyer look over what you have written. I am a lawyer and believe me, it will cost you much less to pay a lawyer now to look over what you've done, before you actually start your network, and fix any mistakes than it will to hire a lawyer in the future to fix those mistakes after you've started your network.
You don't have to hire a lawyer now, but it is wise to do so and it'll save you a lot of money in the future.
You're being in Germany is a bit of bad news. Germany is the most sue-happy country in Europe. There are even specialized lawyer agencies throughout the country that do nothing else but troll local businesses using many loopholes in the local law.
What I'm saying is that it would be wise for you to sooner (better than later) register an LLC (if your project gets any traction) but not in Germany instead in some other country. Then you won't be obliged by the law to display your home address in Impressum and local lawyer trolls won't be able to get anything from you.
For the moment the best advice is to consult a local lawyer concerning legal documents or (if you write them yourself) review similar agreements specifically from German sites. You'll find there some unique shit that doesn't exist in other countries.
Addition: I totally forgot that to register an LLC in Germany you have to put 25.000 Euros on the table as the backup capital. Not everybody has that much money. In France it's about 8.000 Euros but from what I heard from some people who tried entrepreneurship in France, it requires strong nerves to deal with their bureaucracy. In Spain it's about 3.000 Euros and I haven't heard much of a complaining. Anyway, I'm not an expert and you should certainly look around and research various countries in your neighborhood (and perhaps farther away like Hong Kong or something).