Earthlingo is a vocabulary learning game. You play as an alien trying to learn an Earth language (English, Danish, Dutch, French, German, Japanese, Spanish or Vietnamese).
Think of Earthlingo as an interactive picture dictionary with built in revision. The game world lets you associate each word with a location, improving recall.
Earthlingo currently has over 1000 nouns, adjectives and verbs for each language. The number of words and languages will increase over time.
For learning sentence structure and grammar, I’d recommend Pimsleur, or podcasts like JapanesePod 101.