[Zuph]

That works once you've reached a certain level of understanding. Most AAA games have really good translations.

The trick is "comprehensible input." If you can provide a learner with input that is just a little beyond their level of comprehension, they will learn much, much faster. Dump someone into an ocean of complex grammar and vocabulary? It's a nightmare. I can see definite value in a game that starts very basic, and increases complexity as you acquire a language.

A game would also be good for reinforcing word-image links without translation. Sites like DuoLingo do a very good job at training people to be translators, but a poorer job of training people to become adequate speakers, writers, and listeners.