To unlock Hectic, you need to go to the first level, and shoot EVERY explosive barrel in the level, EXCEPT for the first one you see when on the staging platform. After you shoot the other 9 barrels, use the teleporter (Hidden in one of the walls in the main corridor) to return to the start of the level. Then, shoot the barrel you left and turn directly behind you, and go into the room with the berzerk pack. There will be an open teleporter- a blood stain marks the entrance. Be sure to hurry- it doesn't stay open long!Once you get here, good luck- some consider this one of the hardest Doom levels ever made! Once you beat this level, you unlock the Features menu.