if the game is self-voicing or uses some kind of TTS on your system, you can put JAWS to sleep.
From within the game, press insert+6 on the number row
Next, type sleep into the search field, and one of the options is "sleep mode"
Turn that on and save the option.
If you alt+tab out of the application, JAWS will be there again.
Note: If the game did not have a configuration file associated with it previously, there will be a dialogue asking whether or not you want to create a new file with the name of the application in focus at the time already filled in.