First of all, he has stated multiple times that he doesn't want to INSTALL anything. He is wondering what games can be played off of a usb flash drive. He doesn't want admin rights, or want to use up HDD space or anything like that, he simply wants to know what games can be played from a flash drive without requiring an installation.
Second, he also stated that he intends to play these games only after he is finished with his work. And no, don't try to say he always has something to do, because that's not true. I've been to high school, and college, and there is tons of downtime once you have work finished.
I realize he is being sort of immature about replying and the whole situation, and I understand where you are coming from with your points, but his question is a technical one, and it should be treated as such. The background really doesn't matter all that much in this situation.
To the OP, the only game that I can think of are World of Warcraft which has already been mentioned and I know you aren't interested in. I'm a fan of shooters, but only major ones like CoD, which I'm pretty sure requires steam.
Good luck with your search for games!