I don't know what they're scoring on; they've not elaborated on that. However, when I first read into OpenAI it looked like many of their game links were to simply view the screen. To that end, it wouldn't surprise me if they're identifying things you'd otherwise visually see in the game and simply working off them. To use internal states not immediately visible to the player would be sort of disingenuous IMO.
Does this not become something similar to supervised learning if you are scoring internal states of the game? (i.e. scoring on more than just the outcome and things that violate the rules?)