On the title screen hold ALT + S + F and a new menu item will be activated with the name 'Sound Effects Test'.
When you're choosing difficulty level, choose Champion Level and then keep pressing the right arrow key about 6~8 times.
At the Start Screen, push the numbers 2,0,9, & 7 at the Same time then you will get extra options and more debris.
Hold R + E + I + N while fighting and scraps of metal will fall from the sky.
In the difficulty menu, press the keys O + M + F simultaneously.