It is in fact a port of a PC version, released a year back, from the ludicrously prolific Spiderweb Software, a Seattle-based company that has been producing full-length RPG sagas for decades. Minimalist in design, and unashamed in their reuse of assets, the essentially one-man team (Jeff Vogel) produces epic stories that tend to span over three or six 50 hour games. They exist in a world where BioWare never was, and it was up to Spiderweb to advance things from Ultima. And it works. Compellingly.
Vogel's two most recent games - a relaunch of the very long-running Avernum series, and a brand new story in Avadon - have been developed for iPad and Android tablets alongside his traditional PC and Mac. And it turns out this is just about perfect. A week's holiday in France almost didn't get a look in as I began exploring The Black Fortress on my Android Transformer Prime, and a day hasn't gone past since when I don't find a sneaky chance to explore for another hour.