Recently we had a case where one of our users wanted to submit an entry for Mario Calculator, which was rejected because it's not considered a game. As a result Animal Crossing Calculator was also removed from IGDB.
Looking at the guidelines for non-games it states the following:
Software must be released for an older closed platform dedicated to playing video games. For example I Am a Teacher: Super Mario Sweater is a program for designing sweaters on the Famicom Disk System.
I think it would be helpful if there was a more detailed description on which platforms qualify and which don't. An "older closed platform" is very vague, and it's not clear where the line is drawn.
I also stumbled on a post from dleo about this. If DS does indeed count as being "old enough" for non-games, wouldn't both the Mario and Animal Crossing Calculator qualify, since they had DSi releases?