Steam added the ability to add free games to the library without a startup download

There is a new helpful feature on Steam that Valve has not announced.

The new feature is an "add to library" button. This option will allow you to add new games to your Steam library without first downloading them.

This option can only be used when adding free content (games and add-ons). Paid titles will still only appear in gamers' libraries when they have paid for them.