I've just finished the first two games. My times are:
Avernum 2: 88h
I have a tough time getting through these games. Not so much difficulty, but moreso the long time it takes to get through. Usually if the game is similar length to Baldurs Gate 1 and 2, I will mostlikely finish it. Is Avernum 4-6 the same as Avernum 1-3 in that aspect? I looked on how long to beat and it states that Avernum 4 is 60 hours while Avernum 5 and 6 and 39. That's a big difference and yet I somehow find it hard to believe.
I wanted to give Avernum 4 a chance to complete it, but don't want to spend a ridiculous amount of time to do so.