I suspected it was something like that. Too bad; the n2a cards are a good solution for people like me who are afraid of bricking their Nooks. I'm really only looking for a way to get interactive fiction on my Nook STR. Someone on the forum told me about Twisty, a Z machine originally created to render Infocom games and is being used for the newer interactive fiction. Twisty runs on Android and eInk seems perfect for the genre although I don't know how it handles the on-screen keyboard.
I've started rambling. Thanks for the quick reply.