I belive you can bypass the client requirement by firing up the game using the executable, in which case i'd assume the client is only tied to the launcher. I'm not sure and i can't verify it.
Yeah, I assumed this as well, which is why I put the question mark there (amok also didn't seem sure about it). I have F3 on Steam, so I'll get to it eventually.
I think the same is going to apply to other games with launchers. Which reminds me I forgot about the Space Quests.
Not sure about F3 yet no, and dont have it downloaded here and can't until later. If I remember correctly there where two executables for F3, one for the launcher and one for the game, the launcher was tied to Steam, but not the main game executable. This may have been fixed later though.