Repost from my thread from Donglabs.

Image of the solar storm, there's a very heavy portal storm sound from HL EP2 ingame, and a powerful shaking effect [making it super dramatic, woo!] , and you get knocked over and start burning for a while, additionally, all the glass windows break, and power fails, looks boring in the picture, though.
The only problem is that, again, you are affected even inside the maint tunnels, i haven't found a good way of coding something that will leave regular players safe from it, as long as they are in a tunnel.