Check out "Moon" if you want to watch aa awesome Sci-Fi psychological thriller. The only person in the entire movie is Sam Rockwell.
Dude, I've got to warn people, NOT everyone would see it the same way as you. I'd say it was better than you would expect for a 1 man Sci Fi movie, but I think its safe to say, you have to be a real sci fi fan to enjoy the movie.
Oh, and didn't they have a couple of unknowns show up at the end, when the repair ship showed up, I don't think you saw their face though, and they definitely didn't have much more of a role than being a prop for a few seconds, so I won't take away the claim the movie was a 1 man show. Then again you could argue the robot/computer was a character.