Woah.
The best flash that I've seen in a while, so I'll do this with style:
Art Quality (Clearness, Contrast, Mood, etc.) and Content: 2.5\2.5
If I were to base LongLongCat's flash skills on this alone, I would definitely say he's the god of flash. The colors and details of the scenery (like the minefield in the lobby) and creatures (the red quadrapedal monster with the eye for a butt in the lobby) set a mood of fear and unwelcomeness.
Sound: 2.5/2.5
The sound contributed a lot to the horror factor and mood of the whole flash. the grunts, groans, and miscellaneous noises of the demons make everything more disturbing. The credit song just lays on to the tragicness of the ending.
Plot: 2.5/2.5
In a world of clichés, this is masterfully original, and a slightly ambiguous ending keeps you thinking about this flash for hours after viewing it.
Horror-ocity: 2.5\2.5
I love to watch horror films for fun. Alot of them don't even phase me. At first, after I had finished watching this, I thought, "This is a little creepy," but four hours later, in an empty house, I was scared so badly that I would soil my pants.
Overall: 10/10
Awesome. Just plain awesome.