Help with effects

I need to get two effects:

  1. The effect where particals pass by Gman in the intro of Half Life 2.

  2. The masking effect also in that intro that shows stuff in Gmans face.

I want to know how to recreate them in Hammer.

Look at sdk_trainstation_01?

Okay yeah I found the env_starfield, but what about the mask effect?

env_starfield and env_screenoverlay