Please don't be confused by the earlier explanations of holes in the GPL, while they exist, they must either be designed in, or consume quite a bit of time to implement, or both.
Please stop pushing the GPL and tellling people it's their solution, and not to worry, because things will be okay. It's wrong. Because you are not offering a guarantee that your claims are correct, just assurances.
You have a serious case of reading comprehension failure.
Aukustus, if you want to be sure the GPL offers you the protections you want for your code, ignore all of Omnivore's posts. He has continually been giving flawed advice. Read the GPL. Consider how you could use someone else's code, in different ways, were it licensed that way. Consider how you don't want your code used, and how the license prevents or allows that. It should be very clear that it either protects you enough, or it doesn't. If it isn't clear enough, then GPL is not for you. Anyone who offers any other advice, likely has an agenda like Omnivore.
Yes I have an agenda, I want to see more open source roguelikes, don't particularly care what open source license is used. But since you can't read English you just don't get it.
Read the license, decide for yourself.
Which is exactly the advice I gave... repeatedly.. with links.