I've also played this level through multiple times today, I've found a variety of secrets each time that I didn't the first time through, like the secret door to the right of the level entrance and the chain gun outside, but this one is eluding me;
Somewhere there is an entrance to this room, I can see kind of where it is visually without the map up, it's at the far end of the room past the chainsaw, but I've explored all over this map and not found the secret door/wall panel/whatever this is hiding behind.
How can I get the chainsaw in Nuclear Plant – E1M2?
Best Answer
I always struggled with remembering how to get this as a kid playing through this game.
The area that opens after you hit the switch in the center of the slime is very dark. use your map to avoid getting lost.
Compliment of http://www.classicdoom.com/pce1m2.htm.