The answer is yes! Offline mode allows you to play games without connection. First, make sure the ”remember my password” box on the login is checked and all your games are updated. Go to Steam, settings, account, to ensure that the box for “don’t save account credentials on this computer” is not selected. Then go to the menu and select Go Offline. Click Restart in the Offline Mode.
Keep in mind that you will not be received important updates while offline. Always manually close Steam before shutting down your computer. Most games will require an online start before they can work offline. Some other games, might not work at all on offline mode.