I think the way Duolingo executes language learning is great. It's a really fun way to understand the basics/vocabulary and the gamification keeps you interested. Unfortunately, as most users have noticed, Duolingo does not have all languages.
So far, I've only found flash card type apps. The best alternative I found was Memrise.
Are there any other Duolingo-type apps out there? When I mean by similar, I mean similar in the way Duolingo separates its categories and have them build on each other. Of course, there should be some gamification aspects as well.