I remember seeing the Subspace Window open... and not seeing what came out. Its size suggested a Demon or something, that'd be cause for alarm.
And then the front appeared, its size surprising considering the range I was at. Then it glowed... and as it fired, I saw the rest of it enter my screen. My face twisted into a look of horror as I fired pointlessly into it, almost not hearing Command's call to evacuate. I think the fact that the targeting screen just read "UNKNOWN" scared me just as much as how it appeared to me. It was huge, it was powerful, it was RIGHT FREAKING THERE, and nobody knew what it was.