Best done in level 1-1 being that the level is extremely short. This REALLY IS a nightmare though so be prepared. This setting has massive amounts of enemies and they respawn after about 20-30 seconds. You also get hurt much easier and all enemies have AMAZING aim. Starting from the beginning go to the room to the left but DON’T GO IN. There are 2 shotgun wielding soldiers on the top of the stairs. Kill them from outside the room. Don’t go up the stairs just yet because behind the pillars are 2 more shotgun soldiers. Quickly dispose of them and Sprint up the stairs, grab your 100% armor and get the hell out of there before they respawn. Now Head to the first door. There are 3 enemies on the stage in the middle of the room so shoot them from the doorway. Don’t run in because there are 2 enemies on either side of you when you enter. Carefully take care of them, and the 2 other shotgun soldiers and move on.
There are SOLDIERS O PLENTY in the next room and 2 monsters on the wall. Good luck with this room being that this will most likely be the hardest part of this level. Now continue on to the secret door on the side wall (see SCOUT for details) and kill the 2 enemies in the hall. Grab your health and your armor bonuses and high tail it back out of that secret area and to the next room you need to be in. There are monsters and soldiers in here as well so be cautious. Once you finished with them, open the exit door but BACK UP. Theres a monster in there as well. Kill him, run in and exit. Now if you made it this far, big congrats to you as this took me a while to get.