South Park: The Stick of Truth -
It is the fastest way if you shoot at the venting shaft, use the powder and walk over the fridge upstairs. The alternative rote is to walk over the soldier (literally), while shrunk, and climb over the round route. Then, you can shoot at the spot shown in the screenshot, to get rid of rats immediately. Then, enter the venting shaft and follow it until you reach the exit. The small mice that you find there can be eliminated with one shot.