20.1. Underground | Campaign Duke Nukem Forever Guide
Last update: 11 May 2016
At first your path will be blocked by a small fire. Shoot the extinguisher beside it to put it out and go down the stairs. If you don't have a Ripper, below the stairs you will find a corpse with the mentioned weapon beside it. It will come in handy in the further part of the level, so try to keep it with you.
A bit further you will reach the lowest level of the generator and your path will be blocked by the alien plants. Just go below them
Here your path will be blocked by a still working turbine with a impeller which will grind anything that falls into it - apart from the metal cabinets on wheels that can be found in the area. Push them all (three) into the impellers go stop it.
Go up the nearby stairs onto the upper floor, where you will find an employee room (you can catch up with a few Ego points if you missed any). At its end you will find an ventilation shaft with a loose grate.