Avernum Demo. Yes.

Spiderweb Software were name checked in the infamous (and splendid) Vince D Weller Age of Decadence interview as one of the longest running PC-indie RPG developers. They've just released a demo of the latest blooming of their hardy perennial Avernum. This, the fifth installlment is about you and your statistic-hefting party hunting down an assassin who tried to off your Empress, while avoiding him offing you. Spiderweb stress that no previous experience with Avernum is required to jump in, so for those who found themselves nodding sagely at Vince's decrying of the state of mainstream RPGs, this may be a good excuse to put your bandwidth where your mouth is. Download from Gamers' Hell or Avernum's site (which is full of details about the series, as sites tend to be).