I'm not an expert, but I think this is getting pretty close:
* You can certainly deduct some expenses from the tax.
* You can earn around 8,000 € "tax-free". If you get more, you can substract that amount
* As an indie developer (or as a freelancer or someone with a small company), you are responsible for your own health insurance (but you are required to have one). Public health insurance fees are 15.5% (but it is capped at around 500 € per month, which is still a lot), private might be a bit cheapter, depends on the company
* It is wise to spend some money on a retirement plan, but not a requirement
* Then you pay 30 % in tax (I don't know whether health insurance is tax-deductible)
So, if you make 50K in revenue, you can substract business-related expenses, another 8K for the income that is tax-free and pay 30 % on the rest. That is your income, which can be used for health insurance, pension and everything else (again, I'm unsure whether health insurance is before or after tax).
This is when you are not married. Marriage reduces the tax, but I don't know the numbers.
In opposite, when you are employed, you pay 40.5 % tax, which includes everything (governmental retirement plan, health insurance, "public service fees" (don't know how you would call them)).
* If you are a freelancer and your income depends primarily on the time you invest, you should aim for a higher income, because obvioulsy vacation and sickness don't earn you any money.
* As someone with a product that provides a more or less reliable income stream independent from time you put in, a yearly income of around 40-50K is certainly good and sufficient, to make a living. Eiswuxe said he made 3,500 €, which is a yearly salary of 42K. Not too bad and he can expect to steadily increase it, since more and more games are added to his portfolio.
* Don't be afraid of taxes when you are self-employed. They aren't that much different from being employed. The main differene is that you are responsible for a steady income.
* Go to a tax consultant (Steuerberater). Good ones offer you a free introduction, where you can ask questions. As a gentleman, it would be nice to use their service then at least once (if they seem to be reasonable). They can fill your tax return (Steuererklärung) for around 150-200 €, if you are employed and don't have tons of bills that need to be entered in a computer.
For me at least, talking to a tax consultant gave me a way better understanding of the whole subject and even took away some fears what would happen, if I quit my job and start traveling the world while "only" making 50K in renevue per year on the side with my product.
* You can certainly deduct some expenses from the tax.
* You can earn around 8,000 € "tax-free". If you get more, you can substract that amount
* As an indie developer (or as a freelancer or someone with a small company), you are responsible for your own health insurance (but you are required to have one). Public health insurance fees are 15.5% (but it is capped at around 500 € per month, which is still a lot), private might be a bit cheapter, depends on the company
* It is wise to spend some money on a retirement plan, but not a requirement
* Then you pay 30 % in tax (I don't know whether health insurance is tax-deductible)
So, if you make 50K in revenue, you can substract business-related expenses, another 8K for the income that is tax-free and pay 30 % on the rest. That is your income, which can be used for health insurance, pension and everything else (again, I'm unsure whether health insurance is before or after tax).
This is when you are not married. Marriage reduces the tax, but I don't know the numbers.
In opposite, when you are employed, you pay 40.5 % tax, which includes everything (governmental retirement plan, health insurance, "public service fees" (don't know how you would call them)).
Edit: Added some more info