Have a look at Duolingo if you like Memrise, it's a more in depth language learning tool that uses the same kind of ideas.

Duolingo is great, I use it too and know people who got results with it. I don't think it particularly shines on general vocabulary acquiring though¹, so that's where Memrise or a spaced repetition flashcard system like Anki or any other enters the picture.

¹Actually, this is sort of covered by the translation exercises, but since there is not a system to manage the reviewing of new words you learn there, I think it's inferior to a flashcard system.

I really want to use Duolingo, unfortunately I am learning Mandarin, and it is not available yet. It has been announced, a while ago, that it was in their todo list, but I don't know when it will actually be there. It is not even in the beta language section yet.

sadly duolingo has a very limited set of languages, but for thos it had it seemed very nicely done to me.

Memrise is fine too. Do you use decks Source Language -> Destionation Language, the other way around, or both?

Memrise asks you both ways.