"What did you want to do?"
Translation:Co chciałeś zrobić?
The difference between them doesn't really translate that well to English. I guess "what did you want to be doing", would have this difference implied. But if you need to translate always with all these "implied" things it just gets confusing.
The same with idę do domu being "I am going home" instead of "I go home", but I guess the line needs to be drawn somewhere :D.
Awesome course tough, and these quick replies are pretty awesome, I learn a lot with it !
With "Czego chcesz" on its own it would be fine (But I feel that "Co" is a better option anyway), but if the question is more complex, it only works with "Co".
"Chcieć" generally works with both genitive and accusative. Genitive is required if you talk about abstract concepts like justice or freedom.