Great info but actually, if anything, I think this site makes it painfully clear that there is no official single Mahjong ruleset. I also think this supports my belief that as cool as a "universal" Mahjong app might sound on the surface, I really doubt you'd get a super competitive AI if it were programmed to cover ALL possible rule variants. So, Rocklobster, a few more defining bits might be nice to know as we find you that ideal app: 1) You said English supported, of course, but does that also mean numbers on the character suit tiles and letters on the wind tiles? I guess some purists think that detracts from the beauty of the tiles, but screw it, I don't want to have to play with some reference card by my side to figure out which tile is what. Many of the even English localized versions of these apps DO NOT provide us with this handy aspect. 2) iPhone, iPad, or Universal? 3) How do you want your end of game scoring handled? a) Simple. b) Simple with list of recognized special hands. c) Wondrously complex "build-a-bear" style where the game analyzes the exact makeup of your ending hand (in a sense rewarding your for creating your own special hand).
Hex Mahjong Hex Mahjong is a pretty good one for iOS ($1). https://itunes.apple.com/us/app/hex-mahjong/id790320196
