Start the game. When the 'Sign In?' option appears on the screen, select No.
The Games For Windows Live window will drop down from the top of the screen. Click the 'Create New Profile' button.
Scroll down the next window and click the blue 'create a local profile' link near the bottom of the text block. (Don't click the Continue button)
Enter a new profile name and click the Submit button. The game should now continue in offline mode.
The Games For Windows Live window will drop down from the top of the screen. Click the 'Create New Profile' button.
Scroll down the next window and click the blue 'create a local profile' link near the bottom of the text block. (Don't click the Continue button)
Enter a new profile name and click the Submit button. The game should now continue in offline mode.