Level 32: Grosse
Back to Doom 2
This super secret level is actually quite simple once you know where the Invulnerability Sphere is located. Run through to the main room and open up Secret 1 on the east side. Grab the Invulnerability Sphere and open the door to the north. This releases the CyberDemon.
Use the BFG to take him out while dodging his rockets. His rockets should kill most of the Guards wandering around this room. Once the CyberDemon is dead take out the rest of the Guards. Secret 2 is on the western side of the main room and has Health Packs and ammo.
The other 4 Secrets are located under the four corner pillars. Simply press on them to lift them up and grab the goodies underneath.
Once you’re done head to the north and finish off the 4 Commander Keens. This reveals a Button that when pressed takes you to the next level.