1. How long can you go without playing video games? -- I can go seven days. 2. The situation is entirely different, of course, from #1, but what you have is correct. 3. Also correct.
This is my approcah toward English. Very often, posters would ask: Are these correct? Or can we say this? The answers are often "yes" based on simple grammar approach. If you are interested in knowing what the record time time is that someone had kept playing video games non-stop, you can say " how long can you play video games (without stopping) ?" When you ask a negative question by addin