Graphics is a little bit specific, but you can generalize it and rate the aesthetics, or how the text based mechanic chosen fits the game.
In any case I recommend you justify the way you rated the game, by leaving feedback in the comments, either on what could be improved or the stuff you liked and enjoyed the most.
Remember there is no price, so ratings are not that big of a deal, and I wouldn't expect a text based game to be the #1 in Graphics haha. Feedback is the best way to give something back to the devs that put so much effort in their entries.
Hope it helps, and thanks for asking!