Starting a custom multiplayer game
 

I was looking into starting a multiplayer game, and it looks like the only people you can invite to a game are not only friends, they have to be friends that are currently online.

Is that a Steam limitation, or a game limitation? That seems to go along with the whole "async starting a new game" issue. I would like to think you could start a game regardless of the state of the other person. I'm even ok with them having to be a friend, but forcing them to be online, too? bleh.