Include Image Aid
I think it would be a great idea to include Image Aid so we can get the concept of a word. For example: "Es Spielt" and additional to the voice aid, include some images of someone playing. That would be great!
At Duolingo we already have a website for each word we learn. If in that site the users could upload images or choose between those uploaded we would have a great visual aid. Just like Memrise.