If you gather all of the 1UP's in the game and also beat it without dying once, then you will notice that the music on the Intro screen is different (after the credits complete.) At this point, if you start a new game and then press 'G' then you can toggle on and off God Mode! While in God Mode you are unaffected by gravity, you can rapidly shoot chowd blobs with left click, go really fast by holding the space bar, and rapidly shoot chowd nado's with right click.