Forum member Xian sent me a link with interesting information that Spiderweb Software has canceled Avernum 2: Crystal Souls for iPad, and ceased all future iPad Development.
More information.According to a post on the official Spiderweb forums, iOS 8.3, the latest version of Apple's software which launched while Avernum 2: Crystal Souls was in submission, seriously breaks the game. Once the issue was discovered Spiderweb pulled the game from sale, but it appears that the game-breaking issues run deeper than first thought. So Spiderweb has decided to cancel the release of Crystal Souls on iPad altogether. In another post on their forums, Spiderweb goes into the reasons they will no longer be developing for iPad going forward. In short, the games just don't make enough money to justify it.