Pretty short, but otherwise, looking good.
Reminds me of the 1st time that I went through Doom 3. I was oftentimes caught unexpectedly while I was moving through (and sometimes got so spooked in the process that I actually jumped and self-disoriented my character's aim in the process). Oftentimes, I got some form of early warning, such as some sort of sound, a change in lighting, or even one of those "hallucionary cutscenes" that popped up throughout the game, but I was never sure of how soon something was going to lunge out at me. (There were two memorable scenes, one in the original campaign of Doom 3, the other in its expansion pack Resurrection of Evil, that were devoid of any action for an extended period of time, but still managed to keep me on my toes expecting an attack of some sort to happen at any moment due to the aforementioned effects.)
That flash demo looks nice. Looking forward to seeing more of this.