Relative clauses

This morning during our library chat, J was killing the relative clauses. While describing the various tests he accomplished in a videogame this morning, these kinds of sentences were veritably streaming out of him: 

Ich habe alles geholt, was ich holen musste.
Ich glaube, das war der erste Test, den ich geschafft habe. 

I was especially excited about that masculine accusative singular relative pronoun, especially in combination with subordinating word order. There were 3-4 examples of this. I don't believe I heard a single error in basic grammar and syntax. 

By the way, the videogame was "School of Dragons," based on the movie How to Train Your Dragon.

In his description this morning, J was also using a lot of terminology from this book we have just acquired and been reading. 

So today was a very good example of how books + videogames can be used to leverage a lot of active L2 production. I've just ordered a large German World of Warcraft book in order to better be able to do this with that game.