Hello,
I got Avernum: Escape from the pit from steam a few days ago, and everything was going well, but today it just doesn't launch - I click the launch button in the steam window, and a popup comes up saying "Preparing to launch Avernum: Escape from the Pit", and it then it blinks the word "starting..." for a fraction of a second in the game list, and then nothing happens. Everything was working fine yesterday. I vaguely remember it downloading some sort of an update for Avernum, I wonder if it's relevant?
I'm using a Mac with Lion.