You might have to press the green flag twice for the game to start. Arrow: Move. Space: Shoot. At 25 or more points press E to use juggernaut serum. MG-42 unlocks at 30 points (press 3 to use). Press G to use Grenades. Press F for a temporary Flash to brighten up the area. Zombie types: 1.) Normal 2.) Scientist (runner) 3.) Hazmat 4.) ???
You find yourself going deeper into the German facility finding a top secret folder, but all of a sudden the lights go out.