What is Offline Mode?
Offline Mode allows you to play games through Steam without reconnecting to the Steam Network every time you wish to play - this is particularly useful if you do not plan on playing over the internet and would prefer not to download new updates for your single-player games.
Please note that you must connect to the Steam Network and test each of the games you would like to use in Offline Mode at least once to set up your account and configure Offline Mode on your machine.
Using Offline Mode on a PC.
Please follow the instructions below to configure Offline Mode on your PC:
1. Start Steam online - make sure the Remember my password box on the login window is checked
2. Verify that all game files are completely updated - you can see the update status for a game under the Library section (when the game shows as 100% - Ready it is ready to be played in Offline Mode)
3. Launch the game you would like to play offline to verify that there are no further updates to download - shut down the game and return to Steam once you have confirmed that the game can be played
4. Go to Steam > Settings to ensure the Don't save account credentials on this computer option is not selected
5. From the main Steam window, go to the Steam menu and select Go Offline
6. Click Restart in Offline Mode to restart Steam in Offline Mode
Important: The Steam client application's files must be updated to allow for the use of 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 application's files need to be updated.
Firewall settings preventing Steam from updating itself are the most common cause for this problem. Please see the Troubleshooting Network Connectivity topic for instructions to configure your network so Steam may update if you encounter any difficulties with Offline Mode.