I don't believe that lets the Mac run the appropriate shut down procedure so I wouldn't recommend it. Why are you shutting down anyway? Just put it to sleep when you're not using it unless it's gonna be unused for a week or more.
The next time a game locks up/freezes just press and hold "command option() escape" to force quit the game.The computer locked up while playing a game, and I had to shut down by holding the power button for like 7 seconds. .