STALKER: Shadow of Chernobyl is a good start - I used this realism-based mod to make nights extra dark and wounds extra deadly. Anyway, I was wandering through some radioactive wasteland when a blowout occurred - and I had no idea what a blowout was, much less what it looked like.
Here's one - http://www.youtube.com/watch?v=5tJXesjCKxA&feature=related
Basically, if you don't get to shelter in time you get fucked and die. And I was in the middle of nowhere, ages from anyone else. So I started running, spotted a group of fellow Stalkers huddling around a fire in a bus shelter, and ran to there. After a minute the blowout stopped and it was pitch black, with monsters running around everywhere. It was especially frightening when you're huddled in a corner with the panting of a horde of mutants surrounding you.