Play steam games offline without updating
If the Steam client is requiring a login, there is no option to bypass that without going online.
It is for this reason that we encourage users to make sure they understand the behaviors that affect offline mode, so that issues can be avoided.
Most games require an initial start-up while connected to the Steam Network before they will work in offline mode.
If your game's status is "100% - Ready", but you receive the message "This game cannot be started in Offline Mode" when attempting to play offline, the Steam client and/or game files need to be updated.
To run a game without launching Steam, open Windows Explorer, and navigate to the game’s folder in your Steam directory.
If Steam’s offline mode isn’t working at all, you may still be in luck – some Steam games don’t use Steam’s DRM at all and can be launched manually.
If you know you’re going to need offline mode – say you’re preparing for a long plane ride or you’re moving to a new place where you won’t have an Internet connection for a while – you should walk through several steps to ensure Steam is properly prepared to run offline first.
Stored information is required for offline mode to function correctly.
To prevent this information from being lost, make sure that you manually close Steam before shutting your computer down. You'll also want to make sure that you don't have any interfering programs affecting Steam or its installation files.