LiefLayer: In my country, owning a gun is illegal
It's not. Do check your country's laws, but owning a gun is not illegal, just like driving a car isn't illegal. One has to obtain the proper paperwork first (just like in America). The proper papers may be harder to obtain, but one can legally own a gun in Italy, even if they are not a member of the armed forces.
LiefLayer: A gun is made to hurt, no other purpose, it is not useful.
Quite the opposite. A gun is made to prevent one from hurting. Who do you find an easier target, a person with a gun or a person without one? As I said before, a gun can be used as a deterrent to violence, since you do warn the other person in advance that you can hurt them if they attempt to hurt you.
Concealed weapons on the other hand are made for killing, since you do not advertise the fact that you are carrying a gun.
LiefLayer: There are many other ways to defend yourself without using a gun.
Again, the gun isn't there to defend yourself. It is there so you won't have to defend yourself. If you do find yourself in a situation where you do need to defend yourself, a knife may be a better choice, since you'll most likely be in hand to hand combat. If you have distance from your attacker, running away may be better.
The gun talk though is quite off topic with this thread, so I'll drop it.
LiefLayer: Denuvo, does not allow you to know what's really inside the executable (.exe for windows).
This means you may not be able one day to adapt the game if the software company fails or some other reason.
Again, I'm not sure if Denuvo can be used without encrypting the executable. I wouldn't be surprised if it can, but I don't have that good of a knowledge on the inner workings of Denuvo.
LiefLayer: Just for DRM many games today are difficult to adapt, GOG did a huge job, and sometimes was forced to use the floppy disk version (DOS) instead of the CD version (Windows) for that very reason.
I was under the impression that the reason they went with the Dos version instead of the Windows one was compatibility, not DRM. Especially since the early CD-Rom games didn't have any DRM, but instead used the medium itself as a copy protection, since copying CDs was a real pain back in the 95-98 period.
Trilarion: Since you would naturally not want to run programs where the integrity check fails.
That is of course assuming that you do run the integrity check before running the program. And depending on what the program does when you run it, you may need to have more checks in place before allowing it to run.
Let's give the example of a BIOS upgrade. Installing a wrong update can brick your machine, so you are advised to double check the upgrade's validity before running the update. A method that would prevent the update from running if the files were modified could be useful.
Yes, there are times when you need a modified BIOS, so a method to bypass said check would be useful as well. But saying that a DRM-Free software doesn't require checks to prevent it from running if modified is naive.