Go to Episode 8 Part 3. At Mech-Nukem's left arm (the incomplete one), press [Up] close to the path in front of it. You will enter a secret area containing Wozma, the secret Boss. During this time you will have infinite ammunition.
Complete the game on all difficulty settings to obtain the "Thunder gun", which can kill everything in sight. When entering a loading screen or room, quickly tap [Fire]. The gun will fire in all directions. You will get a large health boost and all enemies will be killed.
ACHIEVEMENT - HOW TO UNLOCK Deworming the Big Apple (20 points) - Finish "Rooftop Rebellion". Confucius Say…Die (20 points) - Finish "Chinatown Chiller". Max Pain on the A-Train (20 points) - Finish "Metro Mayhem". I Love the Smell of Sewer Scum (20 points) - Finish "Unholy Underworld". Worker Safety, Last (20 points) - Finish "Fearsome Factory". This Ain't the Love Boat (20 points) - Finish "Tanker Trouble". Going Down Faster Than Enron (20 points) - Finish "Deviant Drilling". Space, the Final Frontier (20 points) - Finish "Orbital Oblivion". My Boots Are Made For Stompin' (10 points) - Stomp on 20 enemies. Pig Out (10 points) - Kill 75 enemies. Glow Like Dr. Manhattan (10 points) - Collect 120 Nuke symbols. New York Minute (10 points) - Finish the first level in under 3 minutes.