hold shift and press the flag to turn on turbo mode, because it is required. space to shoot. kill all the rats. the rat finder (the arrow at the top) tends to get a little inaccurate when you are close to a rat, so if the arrow leads you into a wall, then try turning around.
this game is a sensory nightmare, play with your volume up. (there is flashing lights) play and beat multiple times in a row for a secret.