DUKE NUKEM: ZERO HOUR
When you shoot a fire hydrant in the game stand next to it and press the A button.This will replenish your health to 100.
To access the Titanic level "GOING DOWN" find all the time machine pieces before you get to "THE RACK" and a second exit portal should appear in the room just off the first.
To access the "WETWORLD" level play through level 3 'NUCLEAR WINTER' and when you reach the rail tracks leading to the communicator you have to power up drop off onto the roof below where you will see a medi kit. Now jump off this roof into the water (which is only on 1 side) and swim to a floating platform where you will see the level exit