There's not always a clear divide between original research, and using the subject as a primary source.
Exactly. That is the key point. In the pinball example, looking at the game and playing it a little just to find out what how many points different things are worth is probably ok (<ref>{{cite pinball machine|title=Addams Family|manufacturer=|played=26/7/07}}</ref>) playing lots of games in order to determine how difficult a game it is would be OR. The dividing line is somewhere inbetween - I don't know where.