From developer's website:
The epic conclusion of the award-winning Avernum series. Travel into the strange subterranean land of Avernum, full of dungeons, labyrinths, and constant warfare. A final set of disasters threatens to destroy your homeland in a spasm of famine and warfare. Only you can help your people to get to safety before everything falls apart.
As you wander the gigantic world of Avernum, you will experience:
* An enormous world. Hundreds of quests, dozens of dungeons and enemy fortresses, and multitudes of characters.
* A fascinating storyline, full of surprises, treachery, and epic battles.
* Many unique encounters. Not just mindless hack and slash. Many unusual enemies that will require clever tactics to defeat.
* Rich game system with over 50 spells and battle disciplines, many character building options, and powerful secret skills to unlock.
* Unique game world. Unique races and settings make Avernum different from any RPG out there.
* Experience with previous Avernum games is completely unnecessary to enjoy Avernum 6.