Can someone help me remember this console command?

I remember a while back that I messed around with the timescale of the particles, but now I cannot remember the command! I’ve tried to search in Google.

Also, how can I make a screen overlay, I want plain colors, if possible.

[media]http://www.youtube.com/watch?v=HQfm-3m_4Mg[/media]
(Sorry about the music. The audio got really out of sync, so I swapped it.)

[media]http://www.youtube.com/watch?v=Pv5ffmXDmcA

Looks like phys_timescale and the screen effect is an env_fade

And host_timescale if you also want to mess with the timescale of everything else