I wonder what kind of text this refers to. Is it similar to a game manual, or really a literal description (like what you would have written in the box to give you a general idea of the game, but not going to detail)? Or perhaps just the specs?
In colloquial parlance it could be both and also game review, stuff you can find on gameFAQ and a few other things – generally anything that describes the game in any way would fit. "Opis" here is used as a broad meaning noun, but all these things have also nouns more specific(manual = "instrukcja/podręcznik"; specs = "wymagania techniczne"; review = "recenzja"; FAQ = "FAQ"; solution/walkthrough = "solucja"; tips = "porady"[usually, sometimes just "tips"]).
At least, that's how I understand it. ;-)
It may refer to acting ("Nie podoba mi się jego gra (aktorska)" = I don't like his acting.
Rather not. Its „sztuka” or „przedstawienie”. Both are fine when we speak about actual performance on a stage. However when we refer to a script, only the first can be applied.