The whole "AAA" deal is a joke. Thre are no such things as "AAA", "BBB", "CDCD+" types of games. A game receives its price tag based on many factors (money spent on production, marketing campaign, estimated number of selled copies and general gamers' disposition towards game's genre are the most prominent).
And this is not an "indie" game. It has a publisher (as in the guy who have given money and not a guy who just helps with distribution channels). Granted, it is not a big one but a publisher nonetheless. And for a non-indie game "Tyranny" have a very reasonable price.