Rex Blade: The Battle Begins is a very old & rare FPS in the style of DOOM (Mobygames Link). I've recently gotten horribly stuck on level 9 (world 3 level 3), pretty close to the end of the first episode. To help jog your memory, this level starts out in a big outdoor scene surrounded by enemies (including for the first time a transparent blue enemy). There are two fenced off areas, one with a switch requiring the cytosine key, the other with no visible switch. There is a hangar which you can enter, which should be pretty memorable because it is the first place where enemies stand on balconies above you. There is a terminal in the hangar as well, offering hints like "X marks the spot" and "Pay close attention to the ground".
The only visible possibility to make progress is a flashing square of light against one of the outdoor walls. However, when I press space (USE) on top of it I do not hear the switch sound effect I'm used to (which is played even for secret switches), and as far as I can tell nothing opens up. This may be some kind of a glitch. In fact, this game is so rare it may not even be possible to beat!
I have spent over an hour here pressing space all over the accessible part of the map, to no avail. I've tried it both with the Domination shareware and the original Rex Blade.
So I guess I want to ask, does anyone know what to do here? And if not, does anyone remember actually completing the published game without cheats (which would give me some hope?)