It was a 2. Then I figured out the TOZT & VISR mechanics.

Wonderful scenario for its unique features.

However, its not a 4 because this scenario is not scary at all.

Marathon Evil's Devlin encounter, Marathon Apotheosis Assassin enounter, heck even Marathon Eternal scared me more with the first Wraith encounter.

Also the level itself will get you hung up on just about everything.

EDIT:

I take a little back. While the scenario itself isn't scary, if you forget to turn off the scripting your other scenarios will literally be haunted.