I'm thinking of sleeping and playing video games at work
Why would you do that at work?
It is a good use of my break time.
I think that is too much to do during break time. Maybe just eat lunch instead of taking a nap, your boss will get mad if you play videogames.
It's fine. I have an excuse for first time and some of them might be happy I am taking a break.
If you do all of this during your break, your boss will think you are not caring about your job. You should do less time consuming things so people know you care about the job more.