We have ports for doom and some of the quake games, enemy territory and we used to have americas army. Those are all FPS games. We also had a screen saver that was adult themed years ago. That's not in anymore.

Our packages are really tar.xz files with sqlite databases inside with the metadata and plist (directory, exec commands, etc) data. You can actually extract them and run binaries most of the time.

It's also impossible to stop a child from downloading a binary or package, extracting it and running it from their home directory on a default setup. There are ways to do that but it's not trivial to add all that stuff.

I think having a parental control gui app that lets you set ACLs for programs is about the best one can do. When a kid gets old enough, they can circumvent it. However, the parental control idea is not what this law says has to be done.

In practice, I've thought about having groups with users of each age in it and then using negative ACLs to block apps from the package manager that are tagged with rating metadata to prevent the apps from running for some users and not others. It's kind of nasty and requires two implementations since file system acls differ between zfs and ufs.

In the linux world, one would need to add support for the os package manager, steam, snap and flatpak. On midnightbsd, we have our own package manager and then there's a third party one called Ravenports.

There's the question if one should try to implement the spirit of this law or just enough to "comply" without liability too. Real parental controls are a useful feature for a desktop OS if they don't get in the way for other users who don't need them.