Hi,
There is a very simple free app, based on flashcards, that allows you to learn up to 3 languages - Croatian, German and Spanish, or even English, if one of the other 3 is your "base" language. The words are separated into categories, and the number of words offered is currently limited, only 150.
Here is the Google Play Store link:
https://play.google.com/store/apps/details?id=com.forapps.android.lukamemocards
Cheers