[revolvingocelot]

>the steam client has an "offline mode"

I know it's unusual for HN, but I read both the GGGP and am a user of the thing under discussion! Steam's settings in that regard aren't "sticky" enough for me. I've set myself to Offline, quit, and then found myself Online often enough under both Windows and Linux that it's just easier to write a little script to keep Steam from connecting to the internet.

Worth pointing out to others that even if offline mode fails and one intemperately starts a game while someone else is using one's library, that user will get a minute or two to save their game before Steam closes the game for them, but my cousins have found this annoying enough that I figured I'd take OS-level action.

Ensuring that the recipient also has the ability to deny Steam internet access allows my cousins to log into actually-offline Steam as me, and play single-player content, while I'm actually-online and playing multiplayer.

[simion314]

I never had the issue with Steam going Online without my permissions on Ubuntu.

One thing that affects me with Offline mode is this scenario,

1 the kid is playing with his friends soemthing

2 I am in Offline mode but I just found a cheap game I want to try, but I would need to go Online but this would kick my son out.

so going Offline is an ugly workaround for my scenario.

[revolvingocelot]

Feh, it works on your machine, eh? :D

But seriously, you need Family Sharing. Make your kid an account, then set your account to Family Share with his. Now, he can play games from your library as long as you're not playing any, even if your account is online too.

So, when you want to play some singleplayer stuff, log into your account and buy and download the game as you normally would, whilst your son plays with his friends. Now kill Steam's internet connection on your computer, and play your freshly purchased cheap singleplayer game without bothering or having bothered your son.