Remember in Nova Prospect, when the lights are turned off, and then the combine throw those neat-o red flares out? This shows you how to do it for Half-Life 1.
There might actually be a better way of doing this, but I don't know about it. Oh, and, I wrote the tutorial at like 4:00 in the morning, so it might be a little confusing.
Pretty neat stuff--flare effect looks great imo--, though I never saw the original scene you're trying to emualte.
The only things I can think to possibly improve it would be to perhaps make the flares a bit bigger, and possibly add a smoke sprite for each flare.
Good job!